Pearls

Pearls hard and generally spherical objects produced within the soft tissue of a living shelled mollusk, typically Pearl Oysters for saltwater Pearls and Mussels for freshwater Pearls, although almost all shelled mollusks have the ability to produce Pearl like objects.

Valuable pearls occur in the wild, but they are very rare. Cultured or farmed pearls from pearl oysters make up the majority of those that are currently sold. Pearls from the sea are valued more highly than freshwater pearls.

The Pearl is formed when a foreign body makes it's way inside the mollusk where it acts as an irritant. To combat this, the mollusk secretes a calcium carbonate substance or nacre, around the intrusion which hardens to become a Pearl.

Natural sea Pearls have been sought after for centuries and the only way of harvesting them was to deep dive to retrieve the oysters which were then killed in order to get at the Pearl. The problem with this was that only one in many thousand oysters would actually contain a Pearl and there was no way of telling which did until they were opened. Hence the very high price that natural saltwater pearls did, and still do, command.

Cultured Pearls on the other hand are formed in the same way by the oyster, but each oyster is implanted or seeded with a spherical nucleus, often formed from Mississippi mussel shell of around 6mm diameter. The oyster is then returned to the sea where it naturally secretes it's nacre around the nucleus and will produce a cultured pearl of anywhere between 8 and 16mm in diameter after a period of up to two years.

Cultured pearls are far more likely to be uniformly round than natural pearls and that is why the vast majority of strung Pearl necklaces are cultured pearls as it is now almost impossible to match enough natural pearls by size and color to form a necklace. Even for cultured pearls, a good string of uniform gems can cost hundreds of thousands of dollars.

Most cultured pearls now come from China although Australia and Japan still have good sized Pearl farming industries.