How does an Oyster make a pearl?
The first thing to know about oysters and pearls is that not all oysters make gem quality pearls and some species do not make pearls at all. There are two basic groups of oysters, edible oysters and pearl oysters.
Those that are edible, come from the Ostreidae family. Oysters in this family include the Pacific Oyster, the Wellfleet Oyster and the Belon Oyster. Edible oysters are often referred to as true oysters.
Pearl producing oysters are from the pteriidae or feather oyster family.
Oysters from this family are able to produce both natural and cultured pearls. Pearls are created when a foreign substance gets inside the shell of an oyster. The material is annoying and abrasive to the oysters unprotected soft body. The irritant is quite often a parasite that gets into an oysters shell and not a grain of sand., as many people believe. To counter this irritant the oyster begins to produce a substance called nacre. Nacre is better known as mother of pearl. The oyster covers the foreign material or parasite with layers and layers of nacre which forms a pearl.