South Sea Pearls
Cultivated primarily in Australia, Myanmar, Indonesia, and the islands of the South Pacific. They are produced by the oyster species Pinctada maxima. South Sea pearls tend to be both the largest and the rarest of pearls. Their rarity is due to the fact that growing larger pearls requires a great deal of time, during which many things can go wrong: the oysters can die, the pearl can become misshapen, etc. Thus, South Sea pearls tend to be among the most expensive of pearls, commanding high prices for quality specimens. Their most common colors are white, silver, and gold.
Akoya Pearls
(Grown in Japan and China) Akoya pearls are the classic cultured pearls of Japan. They are the most lustrous of all pearls found anywhere in the world. In recent years, China has been successful in producing Akoya pearls within their own waters. However, at this time they are unable to produce as brilliant a luster as high quality Japanese Akoya cultured pearls. The Akoya pearl is either white or cream in body color and can have yellow, pink or blue hues. Some Akoya pearls achieve a rosé or green overtone. It typically has an excellent, good or fair luster, which is why the Akoya is such a prized gem. The best pearls have clean surface quality and acceptable nacre. The most highly valued Akoyas are larger, have excellent luster and clean surface quality. Only one pearl and maybe an accidental Keshi pearl is harvested from one oyster. This is one reason why seapearls are usually higher price than freshwater pearls...several freshwater pearls can be grown at a time in each clam. The Akoya pearl oyster Pinctada imbricata has been fished for pearls for centuries and is amongst the most widespread of the pearl oyster species. Akoya oysters are found on areas of the eastern coastline of North and South America , the east-coast of Africa , the Mediterranean and throughout the Indo-Pacific. Most notably, the Akoya oyster is found in Japan , where it has formed the basis of a multi-million dollar pearling industry. The Japanese Akoya, Pinctada fucata martensii, or Pinctada fucata produces pearls between two and ten millimeters in size, the industry standard for many decades.
Freshwater Pearls
A great irony of pearl history is that the least expensive cultured pearl product in the market today rivals the quality of the most expensive natural pearls ever found. The price-value anomaly is obvious to consumers as they hasten to buy Chinese freshwater bargains. Indeed, pearls from freshwater mussels lie at the center of the liveliest activity in pearling today. Natural freshwater pearls occur in mussels for the same reason that saltwater pearls occur in oysters. Foreign material, usually a sharp object or parasite, enters a mussel and cannot be expelled. To reduce irritation, the mollusk coats the intruder with the same secretion it uses for shell-building, nacre. To culture freshwater mussels, workers slightly open their shells, cut small slits into the mantle tissue inside both shells, and insert small pieces of live mantle tissue from another mussel into those slits. In freshwater mussels that insertion alone is sufficient to start nacre production. Most cultured freshwater pearls are composed entirely of nacre, just like their natural freshwater and natural saltwater counterparts.
The Chinese were the first to culture a product from freshwater mussels, though their centuries-old Buddhas are not true pearls but shell mabes. The first cultured freshwater pearls originated in Japan. Quite soon after their initial success with cultured saltwater pearls, Japanese pearl farmers experimented with freshwater mussels in Lake Biwa, a large lake near Kyoto. Initial commercial freshwater pearl crops appeared in the 1930s. The all-nacre Biwa pearls formed in colors unseen in saltwater pearls. Almost instantly appealing, their lustre and luminescent depth rivaled naturals because they, too, were pearls through.
Tahitian Pearls
The Black Tahitian pearl is produced by the Black Lipped oyster (Pinctada Margaritafera) which is found in the waters of French Polynesia. Natural Black Tahitian pearls are extremely rare since only one out of about 10,000 oysters contains a pearl. The Black Lipped oyster was nearly harvested to extinction in the early 1900's. These oysters were in high demand primarily for the Mother of Pearl which is part of the oyster shell. Fortunately, the Black Lipped oyster was rescued and is now raised in sea farms in French Polynesia. Black Tahitian pearls are cultured in these oysters on pearl farms in the atolls of French Polynesia. Most of these pearl farms are in the Tuamoto and Gambier island groups. The shape, color, and luster of these certified cultured Black Tahitian pearls are natural.
These cultured certified Black Tahitian pearls range in size from about 8 mm to about 25 mm in diameter which is the size of the largest black Tahitian pearl ever found. Black Tahitian pearls 12 mm in diameter or larger are considered to be rare. These pearls can be very large because the Black Lipped oysters grow to be as large as 12" across and to be 10 pounds in weight. Most Black Tahitian pearls are not really black. Colors can be light silver, gray, yellow bronze, green with pink overtone, and peacock with nearly all colors showing in play-of-color on the surface of the pearl.
Species of this shell are widely distributed throughout tropical Indo-Pacific waters from the Persian Gulf to the Gulf of California and from Japan to the southern islands of the Pacific. More specifically, this oyster also is found in the Cook Islands, Fiji, Tonga, Samoa, New Caledonia, the Philippines, Panama and the Gulf of California.
An adult Pinctada oyster can reach a diameter of 30 centimeters (11.8 inches), with a weight exceeding 5 kilograms (11 pounds). Rare specimens as large as 9 kilos (19.8 pounds) have been harvested. This species of oyster demonstrates the peculiarity of undergoing a change of sex normally during the course of its life. Two to three years of growth are required before the oyster is ready for reproduction.
During its female stage, the mature Pinctada lays eggs all year. Only the extraordinary quantity of eggs produced -40 million per specimen- assures the survival of the species in its natural environment, where the spermatozoon must rely on a chance encounter for conception. Developing larva then become prey for all sea creatures that eat plankton, including the living coral of the reefs. Surviving young oysters, once they develop bivalve shells, are called "spats". But they continue to be targets of many predators, including giant rays, octopus, crabs, starfish and trigger-fish.