How is a pearl formed

Pearls are made by marine oysters and freshwater mussels as a natural defence against an irritant such as a parasite entering their shell or damage to their fragile body. The oyster or mussel slowly secretes layers of aragonite and conchiolin, materials that also make up its shell.

This creates a material called nacre, also known as mother-of-pearl, which encases the irritant and protects the mollusc from it. When pearls are cultured commercially an irritant is manually inserted into a mollusc to promote the production of mother-of-pearl. Natural pearls are exactly that, natural, wild pearls are rarely found in nature, hence the price tag they command. Sadly hundreds of pearl oysters are killed by man searching for the natural pearl, which is where cultured pearls come in.

Although the formation and process of the pearl creation is the same, a cultured pearl is formed when the irritant, usually a piece of the mantle epithelium, is introduced with intention into the mantle and grown in pearl farms, many of which are found in Japan and China. The fresh water mollusc bivalves belong to the family of Unionoida which are freshwater mussels and Veneroida which are fresh water clams.

The pearl oyster is a salt water bivalve oyster and belongs to the Pteriidae family, within the genus Pinctada. Please be advised this family of Mollusca is not to be confused with the Osteidae which includes most of the molluscs commonly consumed as edible oysters, unless that is, you like playing a game of chance with the possible outcome of a fractured tooth.

Facebook Twitter Instagram Mail. Pearls are the result of a biological process -- the oyster's way of protecting itself from foreign substances. Oysters are not the only type of mollusk that can produce pearls. Clams and mussels can also produce pearls, but that is a much rarer occurrence. Most pearls are produced by oysters in both freshwater and saltwater environments. To understand how pearls are formed in oysters, you must first understand an oyster's basic anatomy.

Oysters are bivalves , which means that its shell is made of two parts, or valves. The shell's valves are held together by an elastic ligament. This ligament is positioned where the valves come together, and usually keeps the valves open so the oyster can eat.

As the oyster grows in size, its shell must also grow. The mantle is an organ that produces the oyster's shell, using minerals from the oyster's food. The material created by the mantle is called nacre.

Nacre lines the inside of the shell. It's kind of like the oyster getting a splinter. The oyster's natural reaction is to cover up that irritant to protect itself. This eventually forms a pearl.

So a pearl is a foreign substance covered with layers of nacre. Most pearls that we see in jewelry stores are nicely rounded objects, which are the most valuable ones.