Swan Ltd Jewelers

A pearl is a hard, roundish object produced within the soft tissue (specifically the mantle) of a living shelled mollusk. Just like the shell of mollusks, a pearl is composed of calcium carbonite in minute crystalline form, which has been deposited in concentric layers. The ideal pearl is perfectly round and smooth, but many other shapes of pearls (baroque pearls) occur.
Any mollusk is capable of producing a pearl.

A nacreous pearl is made from layers of nacre, by the same living process as is used in the secretion of the mother of pearl which lines the shell. A "natural pearl" is one that formed without any human intervention at all, in the wild, and is very rare. A "cultured pearl", on the other hand, is one that has been formed on a pearl farm. The great majority of pearls on the market are cultured pearls.