How Does an Oyster Make a Pearl?
These beautiful round jewels are the result of a biological process within the oyster as it protects itself from foreign substances. Oysters produce a unique substance called nacre, or mother-of-pearl that lines the insides of their shells. Sometimes a grain of sand gets inside the shell of an oyster, and rubs against the animal’s tender body.
In order to soothe this irritation, the oyster coats the bit of sand with a smooth layer of its nacre. The mineral substance that fashions the mollusk’s shells. As time goes by, more layers of nacre are added, and gradually, a pearl is formed. The most valuable pearls are produced by tropical sea pearl oysters. Common edible oysters have dull shells, therefore, their pearls are without luster.
The most beautiful pearls kinds 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. Cultured pearls are made in the same way. The only difference is that instead of accidental circumstances, a “pearl farmer” embeds a grain of sand into the mollusk. Pearl harvesters open oysters, cut small slits in the mantle and insert small irritants under the mantle.
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.