How Do Oysters Make Pearls?
Most jewelry is made from precious stones, mined from the earth. But pearls are formed inside the shells of creatures known as pearl oysters. Pearls are made of the same mother-of-pearl material that lines the inside of the oyster’s shell.
They are formed when a grain of sand or other foreign object gets inside the oyster’s shell and irritates the oyster’s tender body. To stop the irritation, the oyster coats the invader with layer after layer of mother-of-pearl. After several years, a smooth, satiny ball has formed around the grain of sand, forming a lustrous pearl.
The most beautiful pearls — the kind used for jewelry — are perfectly round. Not all pearls turn out this way, though. Some pearls form in uneven shapes. These less-than-perfect pearls are known as baroque pearls.
Most people think of pearls as being white. They can come in a variety of colors, though. Other common pearl colors include gray, red, blue, green and even black.
Pearls that form naturally inside of oysters are called natural pearls. Sometimes oysters get a bit of help from pearl harvesters, though.
These people open oysters, cut small slits in the mantle and insert small irritants under the mantle. The pearls produced by this method are called cultured pearls.
Cultured and natural pearls are usually considered to be of equal quality. Cultured pearls are often less expensive, though, because they’re not as rare.
While any oyster — and clams and mussels — can produce pearls, some species of oysters are more likely to produce pearls, while others may be harvested primarily to serve as food.