How Pearls Are Made By Oysters?

Most jewelry is carved out of precious metals, gems, and jewels which are found buried in the Earth, but pearls are found inside a living creature, an oyster. Pearls are the result of a biological process which is the oyster's way of protecting itself from foreign substances.

The only type of mollusk which can produce pearls are Oysters. There is also a much rarer occurrence when clams and mussels produce pearls. Most pearls are produced by oysters in both the environments including freshwater and saltwater. You must understand the basic anatomy of oysters to understand how pearls are formed by them.

Oysters are bivalves. This means that the shell of them is made of two parts or valves. The valves of the shells are held together by an elastic ligament. This ligament is positioned where the valves come together. Usually, this ligament keeps the valves open so the oyster can eat.

The parts of an oyster inside the shell include:

• Mouth (palps)
• Stomach
• Heart
• Intestines
• Gills
• Anus
• Abductor's muscle
• Mantle

When oyster grows in size, its shell should also grow. The mantle is the organ which produces the shell of the oyster, using minerals from the food of oysters. Nacre is the material created by the mantle and it lines inside of the shell.

The natural pearl formation starts when a foreign substance slips into the oyster between the mantle and the shell. This foreign substance irritates the mantle. It's kind of like the oyster getting a splinter. The natural reaction of oysters is to cover up that irritant for its own protection. The irritant is covered by the mantle with layers of the same nacre substance which is used to create the shell. This eventually forms a pearl.

So that foreign substance which is covered by the layers of nacre is called pearl. Most pearls which we see in jewelry stores are nicely rounded objects, which are the most valuable ones. Not all pearls turn out so well. Some pearls come out in an uneven shape which is called baroque pearls. Pearls come in a wide range of colors, including white, black, gray, red, blue and green. Most can be found all over the world, but black pearls are indigenous to the South Pacific.

With the same process, cultured pearls are also created but are given a slight nudge by pearl harvesters. The harvester opens the shell of the oysters to create a cultured pearl. He cuts a small slit in the mantle tissue. Then under the mantle, small irritants are inserted. Cultured and natural pearls are considered to be of equal quality. Whereas cultured pearls are generally less expensive as compared to natural pearls.

By: Preeti Narula

Content: https://animals.howstuffworks.com/marine-life/question630.htm