A pearl is a hard, rounded object produced by certain animals, primarily mollusks such as oysters. Pearls can be used in jewelry and also crushed in cosmetics or paint. Pearl is valued as a gemstone and is cultivated or harvested for jewelry.

Pearls have been a source of fascination for centuries. They have been considered the most magical and feminine of all gems and are the only one created by a living organism. Pearls emanate a certain warmth and glow not found in other gems, due to their unique beginnings.Pearls are found in pearl oysters. However, the origin of the pearl mystified humans for centuries. Many theories were put forward regarding the origin of pearls however, it wasn't until the turn of the twentieth century that the relationship between pearl oysters and parasites was discovered.    

Unlike gemstones produced deep inside the Earth, pearls are created by living creatures called mollusks. Mollusks commonly have a soft, unsegmented body and a hard exterior shell, such as a clam or snail has. These animals live in marine and freshwater habitats as well as on land. The evolutionary history of this group extends back some 530 million years, with approximately 100,000 species of mollusks alive today.

A pearl is born

The birth of a pearl is truly a miraculous event. Unlike gemstones or precious metals that must be mined from the earth, pearls are grown by live oysters far below the surface of the sea. Gemstones must be cut and polished to bring out their beauty. But pearls need no such treatments to reveal their loveliness. They are born from their mother oysters with a shimmering iridescence, luster and soft inner glow that is unlike any other gem on earth.

A natural pearl begins its life as a foreign object, such as a parasite or piece of sand that by accident lodges itself in the oyster’s soft inner body where it cannot be expelled.

In an effort to ease this irritant, the oyster’s body takes defensive action. The oyster begins to secrete a smooth, hard crystalline substance around the irritant in order to protect itself. This substance is called nacre.
  
As long as the irritant remains within its body, the oyster will continue to secrete nacre around the irritant, layer upon layer. After a few years, the irritant will be totally encased by the silky crystalline coatings. The result -- the lovely and lustrous gem called a pearl.
   
But how precious pearls are formed from what an oyster regards as merely protection against irritation is one of nature’s most prized secrets. For the nacre is not just a soothing substance. It is composed of microscopic crystals, each crystal aligned perfectly with each other so that light passing along the axis of one is reflected and refracted by the other to produce a rainbow of light and color. Cultured pearls are formed by oysters in almost an identical fashion. The only difference is that man surgically implants the irritant -- a small piece of polished shell -- in the oyster rather than leaving it to chance, then steps aside to let nature and the oyster create their miracle.

Pearls are formed inside the shell of certain bivalve mollusks. As a response to an irritating parasite inside its shell, the mollusk will deposit layers of calcium carbonate (CaCO3) in the form of the minerals aragonite or calcite (both crystalline forms of calcium carbonate) held together by an organic horn-like compound called conchiolin. This combination of calcium carbonate and conchiolin is called nacre, or as most know it, mother-of-pearl. The idea that a grain of sand acts as a "seed" for the pearl is a myth.

Each layer of the pearl is an aggregation of aragonite crystallites packed invariably with their c-axis more or less normal to the layers and their and b axes having fairly well-defined orientations in the plane of the layers. The small imperfections in the orientation of these axes lead to optical diffusion.

Optical reflection at the successive layers is accompanied by a strong scattering or diffusion spreading the reflected light over a range of solid angles .Thus sharp mirror reflections do not exist. On the other hand, an illusion is created that the pearl itself is a lustrous brilliant object. Thus one of the most admired optical features of a pearl is due to an admixture of multilayer reflection accompanied by scattering due to weak randomness in the alignment of crystallites in each layer. A closer examination of the light reflected by the pearl reveals more information about its optical behavior. In a majority of pearls, the reflected foggy image of the source of light is saddled on either side by two diffuse spots of the same color. These spots arise from the inner layers meeting the external surface of the pearl resulting in periodic surface irregularities as in an echelon. The spots will not occur in pearls that are perfectly spherical. The light reflected by the layers gets diffracted at the surface by these external corrugations, thus leading to diffracted images of the source. The different diffraction orders are generally not well separated and are visible only under a magnifying lens. In a perfectly spherical pearl with its layers parallel to the outer spherical surface this diffraction accompanying reflection is totally absent. Observation of a pearl with a point source of light shows that the reflected image of the source is always surrounded by a chromatic diffusion halo. In the case of a perfectly spherical pearl this halo appears in the form of a diffuse circle. The dominant color of the halo is complementary to that of the reflected light. This arises from the fact that light which is not reflected by the layer.

The unique luster of pearls depends upon the reflection and refraction of light from the translucent layers and is finer in proportion as the layers become thinner and more numerous. The iridescence that some pearls display is caused by the overlapping of successive layers, which breaks up light falling on the surface.

Another beautiful optical effect that enhances the appearance of a pearl occurs when a pearl is illuminated over a very narrow region and is observed from a direction nearly perpendicular to the direction of illumination. The entire pearl then becomes visible because any light that gets scattered parallel to the layers gets transported along the layers illuminating the pearl on the way. This is the optical counterpart of the acoustic whispering gallery effect.

Pearls are usually white, sometimes with a creamy or pinkish tinge, but may be tinted with yellow, green, blue, brown, purple, or black. Black pearls, frequently referred to as Black Tahitian Pearls, are highly valued because of their rarity; the culturing process for them dictates a smaller volume output and can never be mass produced. This is due to bad health and/or non-survival of the process, rejection of the nucleus (the small object such as a tiny fish, grain of sand or crab that slips naturally inside an oyster's shell or inserted by a human), and their sensitivity to changing climatic and ocean conditions.

Any mollusk that produces a shell can produce a pearl. Nevertheless, naturally occurring pearls are rare, found in perhaps one of every 10,000 animals. The cultured pearl industry, which has flourished since the early 20th century, has developed techniques to greatly improve these odds. Indeed, more pearls are produced now than at any time in human history.

Through the ages the pearl has been known as the gem of purity and love. The lustrous glow of the pearl imparts and aura of mystery and romance.

Pure, simple and elegant, pearls have always been coveted by Royalty and the very wealthy.

Powder from crushed pearls was slipped into many a drink in the belief that it was an aphrodisiac. When in reality, the pearl placed around the neck, dangled from earlobes or slipped on a finger are much more effective in the realm of Romance.

Pearls

An old Arab legend tells us that pearls were formed when dew drops filled with moonlight fell into the ocean and were swallowed by oysters. The modern scientific explanation is not nearly as romantic but still quite fascinating.

A natural pearl (often called an Oriental pearl) forms when an irritant works its way into a particular species of oyster, mussel or clam. As a defense mechanism, the mollusk secretes a fluid to coat the irritant. Layer upon layer of this coating is deposited on the irritant until a lustrous pearl is formed.

A cultured pearl undergoes the same process. The only difference is that the irritant is a surgically-implanted mother-of-pearl bead or piece of shell. The core is, therefore, much larger than in a natural pearl. As long as there are enough layers of nacre to result in a beautiful, gem-quality pearl, the size of the nucleus is of no importance to beauty or durability.

Imitation pearls are a different story altogether. In most cases, a glass bead is dipped into a solution made from fish scales. This coating is thin and may eventually wear off. The island of Mallorca is known for its imitation pearl industry.

Among cultured pearls, Akoya pearls from Japan are some of the most lustrous. A good quality necklace of 40 Akoya pearls measuring 7mm in diameter sells for about $1,500, while a super- high quality strand sells for about $4,500. The South Sea pearls of Australia, Myanmar, and Indonesia are rarer and larger, with diameters of 10 to 20mm, and cost far more even though they tend to be less lustrous. A 16 inch strand of white South Sea pearls retail for $40,000 to $50,000.

The world record for the highest price paid for a cultured pearl necklace was $2.3 million at Sotheby’s in 1992. The 17-inch strand had 23 pearls with diameters ranging from 16 to 20mm (about the diameter of a dime), with a bead-shaped platinum clasp with 60 round diamonds.

Consumer ignorance surrounding the various qualities and types of pearls is quite pervasive. In fact, many of the industry’s leading pearl producers think that this ignorance is detrimental to their business. Despite the ubiquitous and enduring appeal of the pearl, there are several organizations such as the World Pearl organization, Cultured Pearl Association, Japan Pearl Promotion Society, and Australia’s Licensed Pearl Producers that fund pearl awareness and promotional programs geared toward informing consumers about the myriad variety of pearls and their appeal as jewelry pieces. Competition between different countries such as Japan, Australia, and China (the three major pearl suppliers) often results in advertisements explaining why a particular country’s pearls are superior because of quality, price, size, etc. These groups, representing the industry's producers and retailers, assert that if consumers are uninformed when purchasing jewelry, they might choose something other than pearls, or might purchase a pearl without being aware of the variety offered by the pearl industry. Such unfamiliarity may drive the price of some of the more exotic pearls down due to lack of market recognition; essentially cutting into sellers' potential profits.

knot pearls - In addition to preventing the loss of more than one pearl, knotting prevents pearls from rubbing against each other. This rubbing can result in a chipping of the nacre coating of the pearl around the hole. Pearls are a very soft gem.

Pearls have been a favorite gem since ancient times. Their appeal is universal. Native Americans of the Upper Mississippi River Valley were wearing pearls in necklaces and other ornaments when the early French explorers arrived. The pearls came from freshwater mussels or clams found in the Mississippi and other rivers and streams. They were most likely found while using the mussels for food and the shells for tempering pottery.

Today, pearls are available in several types, natural or cultured and freshwater or marine. Cultured pearls are created by inserting an irritant into the shell of an oyster. The oyster then secretes a pearly coating to cover the irritant. A natural pearl is pearl all the way through. A cultured pearl is mainly a mussel shell bead with a very thin pearl coating.

Although most natural pearls are found in oysters, they also are found in many different species of freshwater mussels or clams all over the world. Natural pearls tend to be irregular in shape and not as desirable as the high-luster, spherical, cultured pearls. However, the free sculpture of a misshapen freshwater pearl has an appeal all its own.

Natural pearls come in a variety of colors. The tones of the freshwater pearls are dictated by the mother shell. White is the most common, followed by pink. Other colors depend on the type of mussels. Big washboard mussels usually have pink pearls, as do the warty backs. Three ridge mussels have pearls in shades of blue-green and lavender. Muskets produce fine pink pearls, and sand shells have salmon-pink pearls.

One pearl dealer in this area recalls a bright blue pearl that was found about 15 years ago. Rumor says the finder bought a farm or ranch with the proceeds from selling the pearl.

For centuries, humans have treasured pearls. The lustrous play of light across the surfaces of good pearls is so attractive that people have paid fortunes for them, even though they have no human use except adornment.

Pearls actually come in many colors, sizes, and shapes, and are ranked in value according to these qualities. Perfectly round ones with a deep glowing luster, particularly in unusual colors that also show an iridescence (or orient), have always been the most prized and expensive; dull, irregular ones the least.

Pearls used to be harvested by divers. However, it is a dangerous occupation and natural pearls of high quality are rare. People have now learned to farm pearl mollusks specifically to produce cultured pearls, small beads with layers of pearl material around them. Oyster larvae (called spat) are allowed to settle in sheltered locations underwater. Once they have attached themselves to ropes or rafts, the young oysters are grown for a few years. Then their shells are opened just wide enough to surgically insert a small pearl bead and a piece of mantle tissue from another mollusk into the soft tissue. This nucleation process provides the oyster with a spherical irritant to coat with nacre, increasing the likelihood of a symmetrical, round pearl. The farmer removes the cultured pearl from the oyster one to three years later. Cultured pearls, produced around the world, account for about 90 percent of all pearl sales.

Natural Pearl

The pearl is the only gemstone which is grown inside of a living organism. Pearls are formed within oysters or mollusks when a foreign substance (most often a parasite - not a grain of sand) invades the shell of the mollusk, entering the soft mantle tissue, and picking up epithelial cells. In response to the irritation, the epithelial cells form into a sac (known as a pearl sac) which secretes a crystalline substance called nacre, the same substance which makes up the interior of the oyster's shell, which builds up in layers around the irritant, forming the pearl

 

Natural pearls are formed more or less randomly, when some sort of irritant becomes lodged in the tissue of an oyster or mollusk. In response to the irritation, the oyster secretes nacre, a combination of calcium carbonate and organic substances, which gradually builds up in layers around the irritant. Over a period of several years, this build-up of nacre forms a pearl.

The size, shape, and color of the pearl are determined by a combination of factors, including the size and shape of the original irritant, whether the mollusk is living in salt or freshwater, and the geographic region where the mollusk lives.

Natural pearls of any commercial value or desirability are extremely rare. Instead, since the early part of the 20th century, cultured pearls have supplanted natural pearls as the most common and available pearls.

Cultured pearls are still actual pearls, grown organically inside of oysters in the same way as natural pearls. The difference is that, in the case of cultured pearls, the pearl farmer intentionally stimulates the development of the pearl by inserting a "nucleus" into the oyster. Thus, the formation and discovery of the pearl are no longer left to chance.

Natural pearls today tend to be found primarily in older jewelry from estate sales, auctions, and so forth -- in other words, existing pearls rather than new ones. However, some natural pearl beds are being increasingly harvested, including beds in the Persian Gulf area and freshwater natural pearls in the United States.

Cultured Pearls

In a completely natural state, only a very small percentage of oysters will ever produce a pearl at all. Of the pearls, which are produced, only a handful will develop to a desirable size, shape, and color; and only a small fraction of those will be harvested by humans. It is commonly assumed that only one in ten thousand oysters will naturally produce a gem quality pearl. Obviously if we relied only on nature, ownership of pearls would still be relegated to only the wealthiest people in the world, and pearl producing oysters would be on the brink of extinction due to over-harvest. As pearls have been a prized gem by much of the world's population for thousands of years, this need has led to the development of cultured pearls.

The cultured pearl was created as a way of guaranteeing a steady supply of pearls and satisfying the demands of the consumer. Cultured pearls are formed with a helping hand. In this case, humans rather than nature introduce the irritant: a bead or nucleus is inserted into the oyster by a technician to create a pearl which turns out every bit as natural as one that originated in the wild.

Pearls have been prized for their beauty and rarity for more than four thousand years. From ancient China, India, and Egypt, to Imperial Rome, to the Arab world, to Native American tribes, cultures from around the world and throughout recorded history have valued these unique, biologically based gemstones - much longer than any other gem.

There are approximately 8,000 different species of two-shelled (bi-valve) mollusks, of which only about 20 types are capable of consistently producing pearls. Natural pearls have always been extremely rare and valuable. Because the layers of nacre tend to maintain the irregular shape of the original irritant, natural pearls which are round or spherical in shape are even rarer still, and are highly prized. Most natural pearls are irregularly shaped.

In the late 19th and early 20th centuries, however, several Japanese researchers discovered a method of producing pearls artificially. Essentially, the technique involves inserting a foreign substance, or nucleus, into the tissue of the oyster or mollusk, then returning the creature to the sea and allowing the resulting cultured pearl to develop naturally. This practice was quite widespread harvesting Mabe pearls. Kokichi Mikimoto is credited with perfecting the technique for artificially stimulating the development of round pearls in Akoya oysters, receiving a patent for this technique in 1916. Although patented in 1916 this technique has since been improved upon and used extensively throughout the pearling world - no longer simply used to cultured Akoya pearls, but freshwater, South Sea and Tahitian pearls as well.

Mikimoto's discovery opened the door to a greatly expanded pearl industry, in which pearls could be farmed like an agricultural crop, rather than simply sought hit-and-miss. These cultured pearls could now be produced in sufficient quantities to make them available to virtually anyone.

The cultured pearl industry has now far surpassed that of the natural pearl industry. Although a market still persists for pearls gifted to us by nature, these pearls are becoming more and more difficult to find, with rare full strands being auctioned for hundreds of thousands of dollars. Today, purchasing a pearl necklace from nearly any store in the world means purchasing a strand of cultured pearls.

Perfect Pearls

Throughout the ages, humans have been enchanted by the lustrous pearl, a gem that has adorned jewelry, clothing, and precious objects for centuries. Some peoples placed an even higher value on the larger and equally lustrous mother-of-pearl shells.

As ancient trade routes gradually expanded and societies developed across Asia, Europe, and even North America, pearls became important symbols of wealth. Still a source of widespread fascination, pearls are now admired and worn by more people than ever before.

Cave Pearls

Pearls are a concentric concretion found in shallow cave pools. They can be spherical, as in these photos, or cylindrical, elliptical, and even cubical they range in size from barely larger than a sand grain up to golf-ball sized. In the tropics, large beds of them may be found. Grutas de Canicas, a cave recently explored in Mexico, contained pearls estimated in the millions.

Cave pearls form when water dripping into the pool loses carbon dioxide and precipitates calcite. This precipitate usually forms around a nucleus of sand, bones, or fragments of soda straws or rafts. The typical roundness is due to the uniform growth of the pearl, not to any sort of rotation due to dripping. A sphere allows the greatest amount of deposition for the smallest surface area and is thus most likely, even if the nucleus is highly irregular. The dripping causes vibrations in the pool, which may prevent the pearls from cementing (with calcite) to the pool floor, though many pearls are found cemented in. Sometimes excess precipitate will form cups or nests around the pearl.

Species Information

Several species of mussel and oyster are of noted concern. Mussel populations found in the streams of the Mid-west United States are in danger of being over-used. Similarly, mussel and oyster species have been under considerable pressure in places like Australia and Indonesia.

Pearls are produce from organisms such as mollusk, clams and mussels. Oysters is one of the type of mollusk

Oysters

Oysters are not the only type of mollusk that can produce pearls. Clams and mussels can also produce pearls, but that is a much rarer occurrence. Most pearls are produced by oysters in both freshwater and saltwater environments. To understand how pearls are formed in oysters, you must first understand an oyster's basic anatomy.

Oysters are bivalves, which means that its shell is made of two parts, or valves. The shell's valves are held together by an elastic ligament. This ligament is positioned where the valves come together, and usually keeps the valves open so the oyster can eat.

These are the parts of an oyster inside the shell:
Mouth (pulps), Stomach, Heart, Intestines, Gills, Anus, Abductor muscle, Mantle.

As the oyster grows in size, its shell must also grow. The mantle is an organ that produces the oyster's shell, using minerals from the oyster's food. The material created by the mantle is called nacre. Nacre lines the inside of the shell.

The formation of a natural pearl begins when a foreign substance slips into the oyster between the mantle and the shell, which irritates the mantle. It's kind of like the oyster getting a splinter. The oyster's natural reaction is to cover up that irritant to protect itself. The mantle covers the irritant with layers of the same nacre substance that is used to create the shell. This eventually forms a pearl.

Fresh water mussels

Pearl mussels live in lakes, rivers and streams. These freshwater mollusks produce pearls that can rival those of marine mollusks in luster and diverse color. And some species of freshwater pearl mussels are known to have produced dozens of pearls at a time. The local freshwater pearls of Europe, Asia and North America have been prized for hundreds and even thousands of years. In the early 1900s, the many species of North American pearl mussels supplied the thick mother-of-pearl needed for the button industry then booming in the Midwest. Today, freshwater mussel shells provide material for bead nuclei, which pearl farmers around the world implant in marine pearl oysters to create cultured pearls.

Regrettably, eastern North America has lost more than 35 species of pearl mussels to extinction in the last 50 years, chiefly from habitat destruction and pollution. Today, conservation efforts are increasing to protect the species that remain.

Freshwater pearls occur naturally, but in recent years a strong cultured pearl industry has sprung up for this product. Freshwater pearls are generally very irregular in shape, with a puffed rice appearance being the most common.

Chinese freshwater pearls are a more affordable, long-lasting pearl that comes in a wider variety of colors than its more widely known cousin: the saltwater pearl. They have a very thick “nacre” layer, which gives them an unparalleled luster and shine. Bourdage Pearls is proud to carry only Chinese freshwater pearls in a wide variety of colors.

Mother-of-Pearl           

Mother-of-pearl is the basic substance which is secreted by oysters and mollusks to form the inside of their shells. It is the same substance which forms pearls.

Until it was replaced by plastic in the mid-20th century, mother-of-pearl was also used to produce shiny buttons for clothing. This was the case in Broome Australia, a well-known South Sea pearl producing area. Before South Sea pearls became the area staple, this small town thrived on the Pinctada maxima mother-of-pearl business.

Mother-of-pearl is now used extensively as the nucleus in pearl cultivation. The shell of a mussel is cut into squares and then run through a process, which rounds the pieces into beads. These beads are then implanted into the oysters, which then secrete nacre upon the mother-of-pearl beads to form the cultured pearl.

History of pearls

The history of pearls is unparalleled. Used in the Bible to denote wealth, a pearl has history more fascinating, spiritual, and regal than any other gem. Never did the crown heads of Europe imagine the new world as the Land of Pearls but pearls from the United States have been sold all over the world.

1897 saw the start of "pearl fever" in Arkansas when Dr. J. H. Myers found a pinkish pearl in Black River. While his was not the first pearl discovered, he is credited with starting the industry. The "pearl rush" was on. Farmers left their crops unharvested; bankers, lawyers, and merchants closed their doors, and hundreds of families relocated to shanties and tents along the White and Blacks Rivers to search the vast Mussel beds.

During the early years, pearl Hunters could wade out to the mussel beds and pick shells by the thousands. What the river yielded in its great and generous gift was astounding. These pearls become world Famous when English royalty selected one of the unusual natural White River pearls to be mounted as a crown jewel.

White River pearling thrived from 1897 to the 1970's. The Gemological Institute of America classified the White River as one of the top seven freshwater pearl streams in the United States.

Natural pearls are works of art, needing very little from man to enhance their beauty. each natural pearl is different - one of a kind. They come in all shapes and sizes, and are fanciful. Shapes referred to as rosebud, snail, angel wing, turtleback, dog's teeth and other baroque shapes work beautifully for earrings pendants, and pins.

The natural pearl, long a symbol of beauty and wisdom continues to fascinate gem lovers.

Pearls in human history

Throughout the ages, humans have been enchanted by pearls and the shells of the mollusks that produce them. For example, archaeological evidence indicates that almost 6,000 years ago in the Persian Gulf region, people were sometimes buried with a pierced pearl resting in the right hand.

As ancient trade routes gradually expanded and societies developed across Asia and Europe, pearls became important symbols of wealth, status and religious belief. Some peoples, including the ancient Sumerians, pre-Columbian Americans and Pacific islanders, placed an even higher value on the larger and more easily obtained mother-of-pearl shells. Still a source of widespread fascination, pearls are now admired and worn by more people than ever before.

Ancient Middle Eastern cultures were apparently the first to value pearls and pearl shells. Interest in pearls later spread to the Mediterranean; in Persia, the gems were said to be worth their weight in gold. By 100 B.C., the Mediterranean enthusiasm for pearls had become a craze, and pearl-adorned objects have been found at archaeological sites across the Roman Empire, from Syria to North Africa and northern France. According to some historians, one of the reasons Julius Caesar invaded Britain in 55 B.C. was to obtain freshwater pearls.

Pearl farm, Seram, Indonesia

Before the beginning of the 20th Century, pearl hunting was the most common way of harvesting pearls. Divers manually pulled oysters from ocean floors and river bottoms and checked them individually for pearls. Not all natural oysters produce pearls, however. In fact, in a haul of three tones, only three or four oysters will produce perfect pearls.

Now, however, almost all pearls used for jewelry are cultured by planting a core or nucleus into pearl oysters. The pearls are usually harvested three years after the planting, but it can take up to as long as six years before a pearl is produced. This mariculture process was first developed by Kokichi Mikimoto in Japan, who was granted a patent for the process in 1896. The nucleus is generally a polished bead made from mussel shell. Along with a small scrap of mantle tissue from another oyster to serve as an irritant, it is surgically implanted near the oyster's genitals. Oysters which survive the subsequent surgery to remove the finished pearl are often implanted with a new, larger nucleus as part of the same procedure and then returned to the water for another three years of growth.

The original Japanese cultured pearls, known as Akoya pearls, are produced by a species of small oysters no bigger than 6 to 7 cm in size, hence Japanese pearls larger than 10 mm in diameter are extremely rare and highly prized. In the past couple of decades, cultured pearls have been produced with larger oysters in the south Pacific and Indian Ocean. One of the largest pearl-bearing oysters is the Pinctada maxima, which is roughly the size of a dinner plate. South Sea pearls are characterized by their large size and silvery color. Sizes up to 14 mm in diameter are not uncommon. Australia is one of the most important sources of South Sea pearls. Tahitian pearls (also referred to as Titian pearls) are also another South Sea pearl.

In 1914 pearl farmers began culturing freshwater pearls using the pearl mussels native to Lake Biwa. This lake, the largest and most ancient in Japan, lies near the city of Kyoto. The extensive and successful use of the Biwa Pearl Mussel is reflected in the name Biwa pearls, a phrase nearly synonymous with freshwater pearls in general. Since the time of peak production in 1971, when Biwa pearl farmers produced six tons of cultured pearls, pollution and over harvesting have caused the virtual extinction of this animal. Japanese pearl farmers now culture a hybrid pearl mussel -- a cross between the last remaining Biwa Pearl Mussels and a closely related species from China -- in
other Japanese lakes.

Pearls in ancient history

Pearls have been prized for thousands of years. Their mysterious beauty is matched by the mystery of their provenance in ancient times. As pearls were traded through trade routes of the ancient world now lost in the mists of time, the origins of some of the most important pearls in history remain uncertain. What is certain, however, is that the most prized of all pearls were oceanic pearls.

Unlike freshwater pearls, oceanic (saltwater) pearls have properties from the sea that preserve their beauty for generations. Freshwater pearls tend to become chalky or milky over a relatively short time. And unlike their freshwater cousins, oceanic pearls are valued for their regular shape and superior size. But the factor in history that made oceanic pearls the most valued of all was their rarity. Early pearl fishers risked the many dangers of the deep to dive for the precious gems.

Today, wars may no longer be waged over pearl beds, but just as in ancient times, divers still face the perils of the deep in the quest for the perfect pearl.

Read on for just a taste of the fascinating place of the pearl in history – its stories and legends, its beauty and mystique.

Throughout history, the rarity and ethereal beauty of pearls has given rise to many myths and legends. In ancient times, Indians believed that pearls were created by a divine power that transformed drops of dew. In Persian mythology, pearls are created from the tears of the gods while another Persian name for pearls is ‘children of light’, revering the pearl as gifts from the gods. The Chinese believed that pearls were created by the power of moonlight.

As trading routes opened from the lands where pearls originated, the ancient legends also spread around the world. The Greeks adopted the legends of the Orient, believing that pearls were created from the dew of the moon, captured by the oysters swimming on the surface of the sea by night. They also believed that a lightning strike at night would create a pearl. Both the Greeks and later the Romans ascribed the Goddess of Love - Aphrodite or Venus - with the creation of the pearl.

In China, where pearl oysters have been gathered for thousands of years in freshwater rivers and the southern coasts, the character for 'pearl' appears for the first time in a dictionary written in 1000 BC.

The Old Testament of the Bible, the Talmud, the Koran and the Indian epic Mahabharata all praise the purity and perfect beauty of pearls.

Since ancient times, three pearl regions of the Orient have been famed for their fertility:

• The Gulf of Mannar (between Ceylon and South India).
• The Persian Gulf.
• The Red Sea.

 

Ancient stories surrounding the Pearl

Throughout history, pearls have held a unique presence within the wealthy and powerful. For instance, the pearl was the favored gem of the wealthy during the Roman Empire. This gift from the sea had been brought back from the orient by the Roman conquests. Roman women wore pearls to bed so they could be reminded of their wealth immediately upon waking up.

Before jewelers learned to cut gems, the pearl was of greater value than the diamond. In the Orient, pearls were ground into powders to cure anything from heart disease to epilepsy, with possible aphrodisiac uses as well.

Pearls were once considered an exclusive privilege for royalty. A law in 1612 drawn up by the Duke of Saxony prohibited the wearing of pearls by nobility, professors, doctors or their wives in an effort to further distinguish royal appearance. American Indians also used freshwater pearls from the Mississippi River as decorations and jewelry.

One of the largest saltwater pearls still in existence is the Hope Pearl, first acquired by Henry Philip hope in the 19th century. It is two inches long, and varies between 3 1/4 and 4 1/2 inches in circumference. It is on display at the British Museum of Natural History.

Pearls of the Midwest

When most people think of pearls, they imagine cracking open an oyster somewhere on a sandy, tropical beach to find the gem inside. But surprisingly, you can find freshwater pearls right here in the rivers and lakes of the United States.

Pearls have a particularly long history in the Midwest. Excavations in the Ohio River Valley revealed fabulous quantities of pearls belonging to the people of the ancient Hopewell culture (200 B.C. - A.D. 500).

And in the early 1900s, Muscatine, Iowa, became the “Pearl Button Capital of the World”, supplying the globe with mother-of-pearl buttons made from freshwater pearl mussels. Today, these same mussels provide the beads used for implantation during the pearl culturing process.

Legacy of the City of Pearls

Hyderabad, the royal city is a blend of the old and the new, having an inherent style and age-old culture, it is a delight to visit. From the magnificent food to the majestic monuments, from its terrific landscapes to a populace steeped in respect and tradition, the city is just full of surprises. One can explore her by lanes, taste the roadside foodstuff, feel the entrepreneurial excitement in the air and get a whiff of the nostalgia as well. It is also the capital of the state of Andhra Pradesh and the only city in the south, where the major language spoken is Urdu. Inhibited by the world's richest royals, the Nizams, it is also the centre of folk arts like shadow puppetry and kuchipudi, which is an ancient dance form.

One of the largest and wealthiest of India's former princely states, the city built its fortune on the trade of pearls, gold, steel, fabric and, above all, diamonds, which some believe remain hidden beneath the foundations of Golconda Fort, precursor to the city some 10km away. Once the most famous diamond kingdom in the world, Golconda was home to the Kohinoor, the worlds most sought after diamond as well as the Orloff, Regent, and Hope, famous for their typically bloody histories. From Nawabs and pearls to the world's hi-tech happening point, the city's journey is fascinating. The sprawling metropolis is finally coming to terms with itself.

A Glimpse in the Past

Historically, Hyderabad owes its existence to a water shortage. It was founded in the late 16th century by the Qutab Shahi dynasty, a line of rulers known for their beautiful "monuments, mosques and mistresses". In 1589, Mohammed Quli Qutab Shah decided to shift his capital from Golconda to the banks of river Musi. Consequently, a city adorned with magnificent palaces and mosques, embodying a style of architecture that was unique to the place - was born .In 1724 taking advantage of the waning Mughal Empire the viceroy of Hyderabad Asaf Jah, declared Hyderabad as an independent State and founded his own dynasty. So begun the dynasty of the Nizams of Hyderabad, a dynasty that would, for seven generations, rule the kingdom, a dynasty whose scions would be included among the "richest men in the world", a dynasty under which traditions and customs of Islam flourished and a dynasty under whom Hyderabad developed into a focus for arts, culture and learning and the centre of Muslim India. The Nizams held sway over Hyderabad until 1948, when the State was merged with the Indian Union.

The Legacy of the Nizams

The Nizams, who ruled from Golconda Fort, have endowed Hyderabad with many landmark buildings, including the Charminar, the Salarjung Museum, the Falaknuma Palace and the Qutab Shahi Tombs. Even for a city that has modernized tremendously in the last decade Hyderabad's rich legacy of Nizams, makes it one of the most fascinating historical places in India.

The Charminar

The Charminar, a symmetrical edifice which was built by Muhammed Quli Qutab Shah in 1591 to commemorate the cessation of plague in the city, has now become the landmark of the city of Hyderabad. The four minarets carved with lotus buds and petals and the central structure, soaring to a height of 180 feet makes it an architectural jewel of the city.

The Golconda Fort

The Golconda Fort is one of the most famous Forts in the south of India. The origins of the Fort can be traced to the Yadava dynasty of Deogiri, and the Kakatiyas of Warangal. The first three Qutb Shahi kings rebuilt Golconda, over a span of 62 years. The fort is famous for its acoustics, palaces, factories and ingenious water supply system. It was also famous for diamond trade and the Kohinoor diamond is said to have come from here.

The Qutub Shahi Tombs

The Qutub Shahi Tombs are situated at a distance of a kilometer from Golconda Fort, these tombs and monuments of the Qutb Shahi Kings are proof of unique architectural excellence, which is a blend of Persian, Pathan and Hindu forms.

Salarjung Museum

Salarjung Museum the single largest one - man collections of the world. If this one-man had not chosen to remain a bachelor the world would have been bereft of one of the greatest collection of antiques. Iam talking about art objects collected by Yusuf Ali Salar Jung, the prime minister to the Nizam. Though Salar Jung III is credited with these fantastic collections, it all started with his father and grandfather.

The Mecca Masjid

The Mecca Masjid, whose construction started by Muhammad Qutb Shah in 1617 and completed by Aurangzeb in 1694, is very close to the Charminar. It is majestic figure with a huge courtyard can accommodate nearly ten thousand men at prayer.

The Jami Masjid and the Toli Masjid-are the other two mosques, having small and modest structure.

Other popular places of interest are The Falakuma palace, the Chowmukha palace and the Regency Mansion, built in 1803. The Husain Sagar Lake, Naubat Pahad, the Birla temple, Osman Sagar and Himayat Sagar, and the Nehru Zoological Park.

The City of Pearls

The storied wealth amassed under the 200-year reign of Hyderabad's Nizams naturally called forth a precious-jewellery industry. From the year 1724, when the Mughal governor Asaf Jah titled himself Nizam al-Mulk and established his rule over central India's Deccan plateau, until 1948, when the Nizam VII Osman Ali Khan's authority was forcibly superseded by the Indian Army, untold quantities of gems and pearls passed through the Hyderabad's jewel shops on Patthargatti Road. Under the Nizams there was always peace and always a strong demand for gems. The mines close to the Golconda fort gave the world the Hope and Kohinoor diamonds, now in the Smithsonian Institution and the British coronation crown respectively. Diamonds aplenty there once were, but it is pearls that have, over time, left the boldest mark on Hyderabadi culture and trade, and today it is the city's pearl dealers who are champions of the jewellery market. According to Sanskrit texts on Gemmology, a metaphysical genre known as ratnapariksa, or "appreciation of gems", pearls join diamonds, emeralds, rubies and sapphires as the five "god-given" stones, or maharatni. The millennia-old Vedic prayer of Atharvan invokes their special power: "Born of the wind and the air / Born of flashing lightning and starlight / May this shell and in it this pearl protect us from danger".

Once retrieved from the fastness of the sea, pearls in historic days, reached India in two ways: from the Gulf of Mannar in Ceylon (modern Sri Lanka) via the south Indian city of Madurai, and from the Arabian Gulf via the port of Goa. Then, the finest quality pearls were said to be Ceylonese; they were uniformly white, and they were rare. Today, Ceylonese pearls are unknown in Hyderabad, but the slightly yellowish ones from the Arabian Gulf, known as Basra pearls, are readily available both in newly restrung necklaces and in precious old settings. In Patthargatti's shops -- some open to the hot city breeze, others crisply air-conditioned -- the pearls most commonly sold today are the freshwater variety from China.

Emeralds and rubies aside, however, Hyderabad does seem an odd city to be at the top of the pearl trade. The ocean is some 325 kilometers distant, and, commercially speaking, the city is a relative backwater compared to booming Mumbai and Bangalore. But any expert will tell you that Hyderabad's commercial position is due to "the high quality and low cost of labor". A visit to a processing centre confirms that behind almost every door in Patthargatti there are pearl sorters, drillers and stringers, each with hundreds of years of family experience.

Japan

Japan has a long history of fishing, thus partially explaining why they have had such a long-standing interest in Pearls and their cultivation. Although fishing is still a big business in Japan and has employed large populations of Japanese, Pearling has traditional and continues to be a very select occupation (often residing only within family operations). Much is the same in Australia. In Australia however, it was again the Japanese who were the first to begin to make a steady business from pearl diving.

Religious references

According to Rebbenu Bachya, the word Yahalom in the verse Exodus 28:18 means "Pearl" and was the stone on the Ephod representing the tribe of Zebulun.

In a Christian New Testament parable, Jesus compared the Kingdom of Heaven to a Pearl of Great Price. Additionally, the twelve gates of heaven are reportedly each made of a single pearl Revelations 21:21, that is, the Pearly Gates.

The Vedic tradition describes the sacred Nine Pearls which were first documented in the Garuda Purana, one of the books of Hindu holy text Atharvaveda.

In Islam, the Quran often mentions that dwellers of paradise will be adorned with pearls:

22:23 God will admit those who believe and work righteous deeds, to Gardens beneath which rivers flow: they shall be adorned therein with bracelets of gold and pearls; and their garments there will be of silk.

35:33 Gardens of Eternity will they enter: therein will they be adorned with bracelets of gold and pearls; and their garments there will be of silk.

History according to various Cultures

Many thousands of years ago, long before written history, early man probably discovered the first pearl while searching the seashore for food.

Throughout history, the pearl, with its warm inner glow and shimmering iridescence has been one of the most highly prized and sought after gems. Countless references to the pearl can be found in religions and mythology of many cultures from the earliest times.

The ancient Egyptians prized pearls so much they were buried with them. Reportedly, Cleopatra dissolved a single pearl in a glass of wine and drank it, simply to win a wager with Marc Anthony that she could consume the wealth of an entire country in just one meal.

In ancient Rome, pearls were considered the ultimate symbol of wealth and social standing. The Greeks held the pearl in high esteem for both its unrivaled beauty and its associating with love and marriage.

During the Dark Ages, while fair maidens of nobility cherished delicate pearl necklaces, gallant knights often wore pearls onto the battlefield. They believed that the magic possessed by the lustrous gems would protect them from harm.

An Old Arabic Legend romantically explains that the pearls formed when moonlight filled dew drops descended down from the sky into to oceans and were swallowed by oysters.

To the Ancient Persians, pearls symbolized moon and its magical powers. The fragment of oldest known pearl jewelry now displayed at the Museum of Louvre in Paris was found in the sarcophagus of a Persian princess who died in 520 BC.

The Renaissance saw the royal courts of Europe awash in pearls. Since pearls were so highly regarded, a number of European countries passed laws forbidding the wearing of pearls by others outside of the nobility.

During the European expansion into the New World, the discovery of pearls in Central American waters added to the wealth of Europe. Unfortunately, greed and lust for the sea grown gems resulted in the depletion of virtually all the American pearl oyster populations of the 17th Century.

Until the early 1900's, natural pearls were accessible to only the rich and famous. In 1916, famed French jeweler Jacques Cartier bought his landmark store on New York's famous Fifth Avenue by trading two pearl necklaces for the valuable property.

Today, with the advent of pearl cultivation, pearls are affordable and available to all. Cultured pearls share the same properties as natural pearls and are grown by live oysters. The only difference is a little bit of encouragement by man.

Since ancient times, the pearl has been a symbol of unblemished perfection. It is the oldest known gem, and for centuries it was considered the most valuable. A fragment of the oldest known pearl jewelry, found in the sarcophagus of a Persian princess who died in 520 BC, is displayed in the Louvre in Paris. To the ancients, pearls were a symbol of the moon and had magical powers. In classical Rome, only persons above a certain rank were allowed to wear pearl jewelry. The Latin word for pearl literally means "unique", attesting to the fact that no two pearls are identical.

Pearls have been considered ideal wedding gifts because they symbolize purity and innocence. In the Hindu religion, the presentation of an undrilled pearl and its piercing has formed part of the marriage ceremony.

In the romance languages (Spanish, French, Italian), margarita means pearl. The word pearl appeared in the English language in the fourteenth century. In the thirteenth and fourteenth centuries, pearls were very fashionable in Europe as personal ornaments. The clothing of both men and women were embroidered with them.

In the Americas, both the Incas and Aztecs prized pearls for their beauty and magical powers. Spanish explorers of the New World found the natives in possession of rich pearl fisheries. For many years, the New World was best known in European cities like Seville and Cadiz as the land where pearls came from.

Most European countries in the thirteenth and fourteenth centuries had laws regarding who could and could not wear pearls. Teachers and lawyers, for example, could not wear fringes or chains with pearls.

Native Americans of the Atlantic Coastal areas and the Mississippi River Basin were the first to collect and use U.S. freshwater mussel pearls and shells. Pearl pendants and ear pendants were worn by both sexes and both pearl and shell were used for decorative purposes on articles of clothing. Some of the tribes used pearls as tributes, reportedly Powhattan (Pocahontas' father) had large stores of pearls received as tribute. Additionally, armlets, pendants, and gaming pieces were made from mussel shell.

Pearls from the new world

The political stability and economic growth that enabled the Renaissance in Europe also led to a new age in pearls. Art and culture were no longer so strictly controlled by the church and pearls once again became a favorite fashion luxury. Venice and Genoa were famed for their pearl markets.

In addition to pearls so keenly traded from the Orient, freshwater pearls were also discovered in many areas of Europe and can still be seen on church vessels and crown jewels that survive from that period.

On the third of his legendary voyages, Christopher Columbus discovered the pearl beds of the Americas and soon a thriving trade was established bringing pearls to Europe from the coast of what is now Venezuela, Panama and later the Gulf of California. The royal and noble houses of Europe including the Italian Medici, the Austrian Hapsburgs and the English Stuarts were among the biggest buyers.

The most famous pearl of this time is La Peregrina, The Pilgrim, which was owned by Phillip II of Spain. It was believed to have bought the freedom of the slave who discovered the gem in the Gulf of Panama. Today, La Peregrina is owned by Elizabeth Taylor. A gift from Richard Burton, through the centuries its owners have included Queen Mary Tudor and Napoleon Bonaparte.

Queen Elizabeth I of England (1533-1603) amassed a wealth of pearls to rival the lavish collections of the Persian princes and Indian Maharajahs. She always wore at least seven ropes of pearls - the longest reaching her knees - and owned more than 3000 lavish gowns embroidered with pearls.

The fashion for pearls spread among the wealthier middle class throughout Europe and in many countries, including England, France, Germany and Italy. Pearl laws were passed aiming to curb the inflationary demand on pearl prices and the outflow of gold.

The passion for pearls continued to grow unabated and through the Baroque age, the Rococo period and the Napoleonic age became firmly established as an essential accessory in any wealthy and fashionable woman's wardrobe.

Around 1845, French explorers returned to Europe with pearls from the South Sea, some dark in colour and larger than any pearls previously seen. Eugénie, Empress of France, and wife of Napoleon, wore these dark pearls frequently, leading yet another fashion for pearls.

In the late 1800s, the world's most prolific Pinctada maxima oyster beds were discovered off the coasts of northern Australia. For hundreds of years, these beds had been fished by early traders and venturers including the Chinese, Macassars and Indonesians, who are now all known to have had established trade links with Australia’s Aboriginal people. The ‘discovery’ of the beds by Europeans soon gave rise to a booming mother-of-pearl shell industry.

The isolated town of Broome became the world's most important pearling port and by 1900 was supplying around 75% of the world's demand for mother-of-pearl shell. Early in the 20th century the port was home to a fleet of 400 pearling luggers and more than 3000 pearlers from throughout Asia, principally from Japan.

Occasionally, the Pinctada maxima oysters yielded natural pearls - the largest and most voluptuous pearls the world had seen. Their discovery caused a sensation and the modern passion for South Sea pearls was ignited that continues to this day. For the first time, the Europeans brought to the pearl beds the 'new' technology of the industrial revolution. Diving systems, for example, meant that divers could reach depths not previously possible. This also meant that rare natural pearls were being discovered in growing quantities.

In terms of quality, size and quantity, their discovery led to an unprecedented era of pearls through the Victorian era in Europe. South Sea pearls were a popular highlight of the World Exhibition of Paris in 1900.

Around this same time in Japan, Kokichi Mikimoto was having his first success in producing cultured pearls – a success that has influenced the history of pearls to this day.          

Shells

The most commonly encountered shells are hard structures built by mollusks around themselves primarily for protection from predators. Shells are mainly made up of aragonite and small amounts of other minerals found in the mollusks environment.

Shells have again a layered structure that is very similar to the pearls and thus exhibit almost all the optical features that we find in pearls. The important structural difference between a pearl and a shell is that the layers of a shell do not close upon themselves as in a perfect pearl. They always meet the external surface of the shell. As a result the shell surface is locally corrugated on a fine scale. Hence, we always get surface diffraction accompanying multilayer reflection. The reflection results in a metallic sheen of the shell and the diffraction orders are well separated from the specular reflections.

As in pearls, here also we find diffusion haloes. While in pearls they are seen in the reflection mode, in shells since they are thin, we can see them in the transmission mode. The halo arises from the diffraction of light by the crystallites of aragonite present in the different layers. Further all the optical properties exhibit marked polarization features.

Most jewelry is fashioned out of precious metals and jewels that are found buried in the Earth, but pearls are found inside a living creature, an oyster. Pearls are the result of a biological process -- the oyster's way of protecting itself from foreign substances.

The formation of a natural pearl begins when a foreign substance slips into the oyster between the mantle and the shell, which irritates the mantle. It's kind of like the oyster getting a splinter. The oyster's natural reaction is to cover up that irritant to protect itself. The mantle covers the irritant with layers of the same nacre substance that is used to create the shell. This eventually forms a pearl.

So a pearl is a foreign substance covered with layers of nacre. Most pearls that we see in jewelry stores are nicely rounded objects, which are the most valuable ones. Not all pearls turn out so well. Some pearls form in an uneven shape -- these are called baroque pearls. Pearls, as you've probably noticed, come in a variety of various colors, including white, black, gray, red, blue and green. Most pearls can be found all over the world, but black pearls are indigenous to the South Pacific.

Cultured pearls are created by the same process as natural pearls, but are given a slight nudge by pearl harvesters. To create a cultured pearl, the harvester opens the oyster shell and cuts a small slit in the mantle tissue. Small irritants are then inserted under the mantle. In freshwater cultured pearls, cutting the mantle is enough to induce the nacre secretion that produces a pearl -- an irritant doesn't have to be inserted.

While cultured and natural pearls are considered to be of equal quality, cultured pearls are generally less expensive because they aren't as rare.

Magical, mysterious, and radiant, pearls are the only gems born of a living organism. They come from the bottom of the world’s oceans, lakes, rivers, and streams. And they emerge from their watery origins perfectly luminous, not needing to be cut and polished.

See the most spectacular collection of pearls ever assembled in a gorgeous exhibition that combines nature, science, history, and glamour.

Selection and presentation of pearls: Pearls are selected for their size and color (hue). Careful color grading is extremely important.

Pearls are then drilled from both sides, often at a place that is slightly flawed. They are then sorted, threaded, and marketed.

Forming Composition

Contrary to popular belief, pearls hardly ever result from the intrusion of a grain of sand into an oyster's shell. Instead, a pearl forms when an irritant such as a wayward food particle becomes trapped in the mollusk. The animal senses the object and coats it with layers of aragonite ("ah-RAG-uh-nite") and conchiolin (“KON-kee-uh-lin"). These two materials are the same substances the animal uses to build its shell.

Structure

In most pearls, the mineral aragonite is arranged in sheets of flat, six-sided crystals. Between each sheet, the mollusk secretes a very thin layer of the membrane-forming protein conchiolin. This composite material is called nacre ("NAY-ker") or mother-of-pearl. The crystalline structure of nacre reflects light in a unique way, giving so-called nacreous pearls their high luster. In contrast, some pearls are not nacreous and instead have a low-luster, porcelain like surface. The needlelike crystals of aragonite in these pearls are arranged perpendicularly or at an angle to the surface of the pearl.

Types of pearl forming organism

Pearls are produced by a variety of organisms, commonly sea mollusks. They are also produced by fresh water mussels, and occasionally, by snails. Some examples of pearl-producing oysters (you don't have to remember these) are:

Akoya pearl oysters (Pinctada fucata).
Black Lip Pearl shell (Pinctada margaritifera).
Freshwater mussel (Hydriopsis schlegeli).
Large winged pearl shell (Pteria penguin).
Abalone (Notohaliotis discus).
Golden Lip pearl shell or white lip pearl shell (Pinctada maxima).

Process of Pearls forming and their various types

Regardless of the method used to acquire a pearl, the process usually takes several years. Mussels must reach a mature age, which can take up to 3 years, and then be implanted or naturally receive an irritant. Once the irritant is in place, it can take up to another 3 years for the pearl to reach its full size. Often, the irritant may be rejected, the pearl will be terrifically misshapen, or the oyster may simply die from disease or countless other complications. By the end of a 5 to 10 year cycle, only 50% of the oysters will have survived and of the pearls produced, only approximately 5% are of substantial quality for top jewelry makers. From the outset, a pearl farmer can figure on spending over $100 for every oyster that is farmed, of which many will produce nothing or die.

A cultured pearl undergoes the same process. The only difference is that the irritant is a surgically implanted bead or piece of shell called Mother of Pearl. Often, these shells are ground oyster shells that are worth significant amounts of money in their own right as irritant-catalysts for quality pearls. The resulting core is, therefore, much larger than in a natural pearl. Yet, as long as there are enough layers of nacre (the secreted fluid covering the irritant) to result in a beautiful, gem-quality pearl, the size of the nucleus is of no consequence to beauty or durability.

Imitation pearls are a different story altogether. In most cases, a glass bead is dipped into a solution made from fish scales. This coating is thin and may eventually wear off. One can usually tell an imitation by biting on it. Fake pearls glide across your teeth, while the layers of nacre on real pearls feel gritty. The Island of Mallorca is known for its imitation pearl industry.

A Perfect Pearl

Pearls come in a wide variety of sizes and shapes. And although most people think of pearls as round, the truth is that irregularly shaped pearls are more common in nature, while perfectly spherical pearls are extremely rare. A pearl's size and shape depend on the species of mollusk that produced the pearl, how long it took to form, the size and shape of the nucleus and where the pearl formed inside the animal. Pearl farmers increase their chances of obtaining large, round pearls by using large, perfectly spherical nuclei. Even so, there are no guarantees. A pearl's size and shape reflect such variables as the temperature and chemistry of the water, as well as the health of the mollusk.

The value of the pearls in jewelry is determined by a combination of the luster, color, size, lack of surface flaw and symmetry that are appropriate for the type of pearl under consideration. Among those attributes, luster is the most important differentiator of pearl quality according to jewelers. All factors being equal, however, the larger the pearl the more valuable it is. Large, perfectly round pearls are rare and highly valued. Teardrop-shaped pearls are often used in pendants. Irregular shaped pearls are often used in necklaces.

Physical Characteristics

Hardness: 2.5 - 4.5.
S.G.: 2.70 (fresh-water up to 2.74).
Size: from microscopic to many centimeter diameter (rare).
Luster - typical pearly luster is termed "orient".
a variety of colors, depending upon the type of mollusc and the water composition (polluted water produces unusual colors!).
body color: underlying color: white - yellow (cream), black.
overtone: "float" (resembles a filmy lacquer): pink / green / blue.

Composition:

~ 86 % calcium carbonate (CaCO3).
2 - 4 % water.
~ 10 % conchiolin (an organic binding agent).
Together, the conchiolin and CaCO3 are referred to as nacre.
Nacre consists of a series of alternating layers of conchiolin and crystals of CaCO3.
The CaCO3 is in the crystal form known as aragonite. 
The typical iridescence of the pearl is due to the series of nacre layers. 
This is referred to as 'orient'(iridescent effect due to overlapping nacreous plates).

Summary: what makes a pearl a pearl?
They must have outer nacre (mostly aragonite) layer to be considered a true pearl.
Thus only pearls from mollusks with a nacreous mother of pearl lining are "true" pearls.

Determine a pearl’s worth

The worth of a pearl is determined by it characteristics mainly Luster, Surface, Shape, Color, Size.

To an untrained eye, many pearls may look quite similar. There is, to the contrary, an intricate hierarchy to pearls and several factors exist that determine a pearls worth. Luster and size are generally considered the two main factors to look for. Luster for instance, depends on the fineness and evenness of the layers. The deeper the glow, the more perfect the shape and surface, the more valuable they are. Moreover, if you can see a reflection of your face clearly by gazing into the pearl, that’s a high quality luster. The foggier the reflection, the less valuable the pearl. Size on the other hand, has to do with the age of the oyster that created the pearl (the more mature oysters produce larger pearls) and the location in which the pearl was cultured. The South Sea waters of Australia tend to produce the larger pearls; probably because the water along the coastline is supplied with rich nutrients from the ocean floor. Also, the type of mussel common to the area seems to possess a predilection for producing comparatively large pearls.

Today, if you want real pearls, you will probably have to purchase the cultured variety. Natural pearls (those made without man’s assistance) have become so rare and expensive, that for the vast majority of people cultured is the only option. However, top quality natural and cultured pearls are identical to the naked eye in terms of appearance and quality. Only under an X-ray machine can a trained eye discern any difference. Cultured pearls tend to have a larger core or nucleus. But, in all other respects, they are identical.

Interestingly, the best cultured pearls are those that come from an oyster that dies after the pearl is removed. Oysters that do not die after the pearl has been extracted produce what are referred to as “Biwa” pearls. Generally but not always, Biwa pearls fetch a lower price than the impending death variety.

Surface

Because a pearl is the product of a biological process, its surface often shows minor imperfections. Furthermore, when a mollusk secretes the microscopic layers that make up a pearl, each layer does not always encircle the entire pearl. These uneven layers create additional irregularities on the surface. As a result, it is easy to distinguish a real pearl from an artificial one by rubbing it gently across your teeth: a real pearl will feel gritty and an artificial pearl will feel smooth and slippery.

The smoothness of the pearl's surface, from clean to heavily blemished, is the next consideration. Cracks or breaks in the nacre are considered damage. Because pearls are grown in an oyster and are organic gems they are almost never flawless. The gem-quality pearl may have minute blemishes when examined very closely, but they are not noticeable at arm's length.

Shape of a Pearl

The shape of a pearl is determined by its location in a shell. Those along the lip are round and are the most valuable. Wing-shaped pearls form along the back of the shell, and irregular pearls form in the heels of shells.

Blister pearls, where the pearl is attached to the shell, are the most common. Some people collect shells with blister pearls, and occasionally a free pearl exists inside the blister pearl.

Similarly, it is very rare to find a perfectly round pearl. The rounder the pearl, however, the more valuable it is. Slightly off-round, semi-baroque and baroque pearls are not as valuable as perfectly round pearls, however, they can be lustrous and appealing and have a natural beauty and value of their own.

Pearls come in eight basic shapes: round, semi-round, button, drop, pear, oval, baroque, and ringed. Perfectly round pearls are the rarest and most expensive, and are generally used in necklaces, or strings of pearls. Semi-rounds are also used in necklaces or in pieces where the shape of the pearl can be disguised to look like it is a perfectly round pearl. Button pearls are like a slightly flattened round pearl and can also make a necklace, but are more often used in single pendants or earrings where the back half of the pearl is covered, making it look like a larger, round pearl.

Drop and pear shaped pearls are sometimes referred to as teardrop pearls and are most often seen in earrings, pendants, or as a center pearl in a necklace. Baroque pearls have a different appeal to them than more standard shapes because they are often highly irregular and make unique and interesting shapes. They are also commonly seen in necklaces. Ringed pearls are characterized by concentric ridges, or rings, around the body of the pearl.

A good-sized irregular pearl can be found in about one in 100 clams. However, a good-sized, natural, round pearl occurs only once in every 10,000 clams.

Color and Overtone

Pearls also come in many colors. The most popular colors are whites, creams, and pinks. Silver, black, and gold are also gaining increasing interest. In fact, a deep lustrous black pearl is one of the more rare finds in the pearling industry, usually only being found in the South Sea near Australia. Thus, they can be one of the more costly items.

Pearls occur naturally in a spectacular array of colors, ranging from white to gold, purple and black. A pearl's color depends on both the species of mollusk that produced the pearl and the environment in which the animal lived. In general, crystals of aragonite are white or colorless. The natural color of a pearl is mostly due to conchiolin, which contains organic pigments.

Cultured pearls range in color from white to black with various multi-colored overtones. The color of the pearl is really the wearer's preference.

Luster

Luster is the most important factor in choosing pearls. The inner glow of the pearl combined with the surface brilliance defines luster. The higher the luster, the thicker the nacre or secretion from the oyster and the stronger the glow. Lower quality cultured pearls appear too white, dull or chalky.

One of the most distinctive features of a nacreous pearl is the way it seems to glow from within. This property, known as "luster," gives pearls their unusual beauty. Luster results from the reflection of light rays not only off the surface of the pearl, but also off the concentric inner layers of nacre. Because a pearl's surface is round, it acts as a convex mirror, reflecting light so that it appears to emanate from within the pearl. The multiple layers of nacre also give rise to the "iridescence" or "orient" of pearls -- a characteristic that resembles the shimmer seen on a soap bubble. The layers of nacre act like tiny prisms, refracting light so that it appears as all the colors of the rainbow.

Luster is essentially the reflective quality or brilliance of the surface of the pearl nacre. The more lustrous the pearl, the more it shines and reflects light and images. In general, saltwater pearls tend to have greater luster than freshwater pearls. Pearls with low luster appear white or chalky, rather than brilliant and shiny.

High luster results at least in part from the amount of nacre deposited to form the pearl, which in turn is a function of how long the pearl has had to develop within the oyster. Pearls with a high luster are generally valued much more highly than pearls with a lower luster. A bit of an exception to this value rule are the keshi or "poppyseed" pearls. Because they are 100% nacre, keshi tend to be the most lustrous of all pearls, yet they are often less expensive than cultured pearls.

Size

Cultured pearls are measured in millimeters. All other factors being equal, the larger the pearl the rarer and more valuable it is.

The largest pearl ever found, so far, came from the Philippines in 1934. It weighed 14 lbs (6.36 kgs) when it was discovered by an anonymous Muslim Filipino diver off the island of Palawan. Later, a Palawan chieftain gave the pearl to Wilbur Dowell Cobb in 1936 as gift for having saved the life of his son. It was first called the Pearl of Allah and is now officially named the Pearl of Lao-tze.

Different types of pearls

There are many different types of pearls in the world, but are they all made the same way? The answer is no. Some are made by man, others are made by oysters, and some are made by oysters with the help of man.

There are essentially three types of pearls: natural, cultured and imitation.

Natural Pearl

A natural pearl (often called an Oriental pearl) forms when an irritant, such as a piece of sand, works its way into a particular species of oyster, mussel, or clam. As a defense mechanism, the mollusk secretes a fluid to coat the irritant. Layer upon layer of this coating is deposited on the irritant until a lustrous pearl is formed.

Natural Pearls are formed when a foreign object, such as piece of coral or parasite, accidentally enters into an oyster.

The irritated oyster tries to get rid of the foreign particle. When it can't, it starts covering the object with layer upon layer of a smooth substance called "Nacre". As layers and layers of nacre build up around the object they form a beautiful smooth pearl. One this process is started, it will continue as long as the oyster is alive. It will usually take many years for a reasonable size pearl to form.

Because foreign objects do not enter oysters very often, Natural pearls are very rare and therefore are the most expensive.

Cultured pearl 
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A cultured pearl is an organic gem. This means that it was produced by a living organism, generally an oyster or a mussel. It is produced by placing a bead inside the oyster. The oyster then coats the bead (with nacre) to produce the pearl.

Imitation (Shell based) pearl

A shell based pearl is an imitation. It is made by painting a shell bead with pearl paint. Be careful of brand named shell based pearls, these sometimes appear to be cultured pearls, but are only imitation.

They sometimes look real, but they're not.

Imitation pearls are made by man out of glass or plastic beads and then coated with synthetic substances such as nail polish to make them look more like real pearls.

These pearls are often given names, which sound like the names of real pearls, but they do not have any real value. People have developed many new and innovative ways to make these pearls, but they will never be able to capture the true beauty and deep-seated luster of real pearls.

Categories of Pearls: freshwater and saltwater

Pearls can come from either salt or freshwater sources. Typically, saltwater pearls tend to be higher quality, although there are several types of freshwater pearls that are considered high in quality as well. Freshwater pearls tend to be very irregular in shape, with a puffed rice appearance the most prevalent. Nevertheless, it is each individual pearls merits that determines value more than the source of the pearl.

Freshwater pearls

A freshwater pearl is a pearl that is cultured in a mussel in a lake, freshwater pearls are formed in freshwater mussels that live in lakes, rivers, ponds and other bodies of fresh water. Most freshwater cultured pearls sold today come from China.  Freshwater cultured pearls are less expensive than the Akoya pearls. Freshwater pearls come in many shapes from round to button shapes, from flat flakes to rice shapes and in many colors.

Saltwater pearls

As their name implies, saltwater pearls grow in oysters that live in the ocean, usually in protected lagoons. The traditional cultured pearl is cultured in an oyster in the ocean (salt water pearls are called Akoya pearls).  As with the salt water Akoya pearl, the round shapes are generally more expensive.

Akoya, South Sea and Tahitian are the three main types of saltwater pearls.

Akoya pearls

Akoya pearls are the most popular type of luxury saltwater pearl sold today. Akoya pearls are perfect for casual or elegant dress and offer exceptional beauty and value. Akoyans have a consistent and desirable perfectly round shape with coloration that varies from very white, to white with various overtones to black. Akoya pearls are unmatched in their perfect roundness, incredible smoothness, and lustrous shine.

Black Tahitian Pearls

Black Tahitian pearls are elegant and sensual and truly add a sense of the mysterious. These French Polynesian pearls are the most luxurious and sought after black pearls. Coloration varies from very black, to black with various overtones to copper.

South Sea Pearls

South Sea pearls are impeccable. They are the best and their beauty is unmistakable. South Sea pearls are an heirloom item. They are quality, refinement and grace. Absolutely breathtaking. Coloration varies from white, to white with various overtones to gold.

Real Pearls

Only living oysters and mussels can create real pearls

If a pearl is formed by a living oyster or mussel, it is a Real pearl. All other pearls are Imitation. Real Pearls can be either Natural or Cultured.

Natural pearls

Concentric layers of CaCO3 are deposited around an irritant. This may be a piece of mantle lobe or some other material.

Only the mantle lobe can secrete nacre. When a piece of mantle lobe is introduced by some accident into the tissue of the oyster, the oyster forms a bag known as a "pearl sac". It is this sac that secretes the nacre around the irritant to make the pearl.

Thus, pearls are calcareous concretions.

Some natural pearls have quite unusual shapes. These are often called "baroque" pearls.

Both saltwater and freshwater pearls consist of the same material and can form in "baroque" shapes. Unless you are quite familiar with the typical characteristics ("look") of pearls from certain specific sources, it would be very difficult to know whether a given pearl was saltwater or freshwater in origin.

Probably the most common freshwater pearl on the market is the Chinese freshwater baroques, some of which are crankily and look like crisped rice. These have been very popular in recent years because they cost dramatically less than Akoya cultured pearls.

Cultured Pearls
 
Oysters and mussels are induced to make pearls. The result is termed "cultured pearls".

Made with a little help from man.

Cultured Pearls are formed when man carefully opens the oyster shell and places an irritant (usually a piece of mantle tissue) inside to 'trick' the oyster into producing a pearl. Once the irritant is placed it is up to the oyster and nature to produce their miracle.

Maybe 90% of the pearls sold are cultured.

If you break a pearl open you will see that it consists of a bead covered by a thin layer of nacre.

The culturing process involves inserting a small piece of mantle lobe and a bead made from mother of pearl shell into the tissues of a pearl-producing mollusk.

The mollusk treats the bead as an irritant and the mantle lobe tissue begins to deposit a nacreous coating over it.

Here is a description and some photographs to illustrate the process. The photographs were taken at the Mikimoto Pearl Museum, Toba, Japan.

Oysters are raised in a tank, allowed to attach to fibers, then grown in sea water for two to three years. Growing oysters are suspended in cages hung from rafts. They feed on plankton. Healthy oysters are selected for pearl cultivation.

The bead is prepared. Mikimoto use Pig toe clam shells, from the Mississippi River. Small balls are prepared from pieces of these shells. An example of a mother of pearl bead.

Living oysters are wedged open and a piece of mantle lobe harvested from an other oyster, plus a bead, are inserted into the soft tissue. This image shows insertion of mantle tissue and bead. Here is a labelled version of this image, showing the important components.

Oysters are then returned to the sea, where they are suspended in cages 7 - 10 feet below the surface. They are maintained and harvested after some time. The culture period used to be ~ 3.5 yrs, producing ~ 1mm layer on the bead, but now the culture period may take less than 2 yrs.
The commercial production method is now known as the Mise - Nishikawa method.

Typical results

5% high quality pearls (hanadama).
28% marketable pearls.
17% unmarketable pearls.
5% uncoated nuclei.
50% of oysters containing nuclei will die.
Source: Mikimoto.

Cultivation of cultured pearl

Cultivation of those charming pearls dates back until the 13th century. The famous Japanese 'Biwa' pearls used to control the industry from 1924 until well into the 70's. The Biwa Lake in Japan, like so many others, became a victim of environmental pollution caused by adjoining factories and urban sprawl. The extensive freshwater pearl production in the waters of Lake Biwa came to an end.

China started its freshwater pearl production just before 1970. Over the years, a more and more remarkable quality was achieved. Today Chinese freshwater cultured pearls dominate the market.
"Hyriopsis schlegeli" is the most commonly used mussel für freshwater pearl cultivation, belonging to the species of Unionides. The outer shell an ordinary brown, the inside yet a glossy white. The maximum size of this mussel may reach 30 x 20 cm. Freshwater cultured pearls, contrary to saltwater cultured pearls, do not contain a mother of pearl nucleus. Pearls exceeding a size of 8mm are an exception. One mussel can be implemented with 20 to 60 implants to grow freshwater pearls. After approximately one and a-half years have passed, the pearls have grown to a size of 3mm. After three years, sizes of 7mm are possible. A larger size can be achieved only, if the mussel remains untouched for more than 4 years.

Freshwater cultured pearls appear in a wide range of colors: white, off-white, champagne, shades of pink and orange, purple, mauve, silver and brown. Their unique shapes cover oval, ovate, button-shaped, and drop shaped. Some show a stunning similarity to potatoes. A beautiful pearl necklace with perfectly round, large freshwater cultured pearls are a rare gem.           

Types of cultured pearls:

There are many types of cultured pearls. Here are some of the most popular.

Japanese Akoya Pearls

 

 

Have you heard of these before? Japanese Akoya are one of the most familiar types of cultured pearls. They are grown in a Japanese pearl oyster called Pinctada Fucata Martensil. Here a bead and a piece of mantle tissue is placed inside the oyster. This helps to grow pearls that are more round. But because the bead is quite big, the pearl is made up of only about 10% nacre and 90% bead. Nevertheless, Akoya pearls are famous for their lovely lustre and warm colors. Their size is generally between 3 mm to 9 mm. Akoya pearls that are allowed to grow at least 3 years are of very good quality and thus very expensive.

Comercial-grade Akoya cultured pearls take 10 to 18 months from the time they are nucleated to the point they're ready for harvest. Akoya cultured pearls are the most difficult and costly to grow because of the low survival rates of their host oysters. Less than 50 percent of Akoya oysters survive the nucleation process and those that do go on to produce pearls can do so only once.

Chinese Akoya Pearls

In recent years China has also started producing Akoya pearls. Chine