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Home > News > Pearls and Pearl Jewelry > Origin of Cultured Pearls: Treasures of the Sea Are a Miracle of Nature

Origin of Cultured Pearls: Treasures of the Sea Are a Miracle of Nature

A pearl starts out as a grain of sand or microscopic worm that works its way into an oyster and cannot be expelled. To protect its soft body from this irritant, the oyster secretes a smooth, hard crystalline substance called nacre. Layer upon layer of nacre coats the foreign object and hardens, ultimately forming a pearl.

Although early pearl gathering depended on divers braving the ocean's depths to retrieve these treasures, the vast majority of pearls today are grown, or cultured, on pearl farms by surgically inserting a small shell bead, or nucleus, into the mantle of an oyster.The first round cultured pearls were cultivated in Japan in the late 19th century. Even though pearls are harvested en masse on pearl farms, producing a quality pearl is an extremely rare event. It is estimated that half of all nucleated oysters do not survive - and of those that do, only 20% bear marketable pearls.

Cultured pearls come in a variety of sizes, shapes, colors and kinds. Akoya pearls, grown mainly in Japan, are the classic round pearls found in most quality jewelry.

White South Sea pearls, grown in Australia, Indonesia, the Philippines and other regions of the South Pacific, are prized for their large size.

Tahitian pearls, grown in French Polynesia, command top prices for their large size and unusual dark shades. Mabé pearls, grown in Japan, Indonesia, French Polynesia and Australia, are flat-backed because they form against the inside shell of the oyster rather than within the oyster's body.

Keshi pearls are naturally created in the soft tissue of most cultured pearl-bearing oysters. Caused by tiny organisms, shell fragments or other irritants, they do not have a man-made nucleus, and are usually baroque (irregularly shaped).

Freshwater pearls are grown in bays, lakes and rivers and are mostly farmed in Japan, China and the United States.