How Do Oysters Make Pearls?
How do oysters make pearls? Most of the popular and formal jewelry people wear is made from precious stones that are mined from the earth. Pearls, however, are not just harvested from bodies of water but are formed inside the shells of the creature commonly known as an oyster. This makes pearls an especially fascinating piece of jewerly and leaves many people wondering how do oysters make pearls.
Pearls are very rare and thus usually expensive. Oysters are the most common producer, and although there are other marine creatures that may produce pearls, they are extremely rare.
To better understand how do oysters produce pearls, it is important to understand the structure and function of an oyster. Oysters are mollusks, and those with the ability to create pearls are called feathered oysters. There are many types of feathered oysters including the gold and silver-lipped, gulf-lipped, Japanese, and Shark bay pearl oysters.
Oysters live and grow within bivalve shells that allow them to eat whenever they require food, through the shell's opening. The shells, when closed, provide them with protection. To protect the oyster’s delicate body from the hard shell, the oyster releases a chemical inside the shell called nacre to cushion itself.
While pearls are fun jewelry accessories for humans, for oysters, pearls are a reaction from their self-defense mechanisms against an external irritant that has entered its shell.
How Do Oysters Make Pearls
Sometimes called Oriental pearls, natural pearls are formed in the oyster’s stomach when an external substance or irritant, in the form of a grain or sand, finds its way inside the shell. To protect itself, the oyster releases the nacre, which is actually the same substance that forms the shell.
As layers and layers of nacre are secreted, the irritant becomes enveloped inside a smooth material. Over time, all these layers will accumulate –like forming a snowball - and eventually they will create a round, shiny pearl.
Pearl Colors and Types
Pearls come in a variety of colors. A pearl can be white, black, pink, blue, green, red, and black. It usually takes an average of three years for pearls to achieve their maximum size. This is why pearls are rare and expensive.
Black pearls are extremely rare and are only found in the South Pacific.
Although many types of pearls are produced, some varieties are not as attractive and therefore possess no commercial value. The majority of the pearls in the market today come from:
- The Philippines
- Japan
- Myanmar
- Indonesia
- Australia
- Tahiti
- China
- India
Cultured pearls are also popular in jewelry making. They are produced the same way as natural pears however, some man-made manipulation is required. In particular, a pearl farmer will have to open the shell of the oyster and cut a slit in its mantle to insert an irritant. Usually a grain of sand is used.
Natural and cultured pearls can be harvested from both fresh and saltwater. Saltwater pears are considered higher in quality since most freshwater pearls have lumpier construction and shapes.
Alternate Theories
There exists today another theory on how do oysters make pearls that refutes what scientists previously believed. According to John Lucas and Paul Southgate, writers of the book The Pearl Oyster, the “irritant theory” is false. They claim that pearl oysters have higher rates of mantle cavity ventilation as compared to other bivalves and that it is therefore not possible for an oyster to expel irritants from its mantle.
Instead, oysters create pearls as a reaction to a mantle injury. When a mantle injury heals, a cyst forms and becomes filled with calcium carbonate coming form the mantle cells. Such excretions form the pearl.
Whichever theory is correct, pearls will always be cherished possessions. Pearls are not reserved for jewelry design alone. Throughout history, pearls have been used for medicine as well. India and China have used pearls to treat insanity and as aphrodisiacs. Pearls are part of the cosmetics world as well. Ground pearls have been used as face masks for acne treatment. Pearl powder is also said to improve skin condition by preventing acne breakouts and reducing skin redness.