A pearl is a small, hard, roundish object created naturally by mollusks or oysters. When a particle of sand gets trapped in the oyster's shell, the inner surface of the shell secretes calcium carbonate that covers the sand particle and reduces irritation. Over time, as more calcium carbonate is secreted, this particle gets transformed into a pearl.
Where Do Pearls Originate From?
Though there are many rare gems, the pearl is the only gem that comes from the ocean's womb. According to a popular Arab myth, pearls were formed when the oysters swallowed dewdrops that fell into the ocean in moonlight.
Though many bivalves like mollusks, including abalone, a large sized sea snail and mussels, create pearls, it is the oysters' pearls that are more sought after. Pearl oysters belong to a family known as Pteriidae, also called feathered oysters.
When a foreign substance enters the shell and resides between the mantle and the shell, the oyster secretes certain chemicals like conchiolin and calcium carbonate to cover it as a part of self defense.
This irritant or foreign object can not only be a grain of sand but anything like animal tissue, parasites or organic debris. The nacre, or inner shell, continues this secretion until it covers the substance by forming several layers on top of it, leading to the formation of a small substance referred to as pearl. This is the way oysters make pearls.
Contrary to the belief that all pearls are perfectly round, the pearl takes irregular shape according to the irritant. These pearls are known as baroque pearls. The formation of pearl takes up to 6 to 7 years.
Pearls come in various tints, ranging from pure white to yellowish white. Other colors found in pearls are white tinted with pink, blue, and green. The most beautiful pearl is the 'rose', a pink pearl of fine luster and color. This variety of pearl is the most expensive.
Where Do Black Pearls Come From?
Black pearls are extremely rare as they are made by a particular species of oysters called Pinctada Margaritifera, otherwise known as black-lipped oyster. This oyster is found in the South Pacific ocean.
As most of the black pearls came from Tahiti, they are known as the Tahitian black pearls. Because of their rarity, black pearls were very expensive. Approximately only one among ten thousand oysters produces a black pearl and only a few pearls are of the required shape, size and luster.
The most valuable and rarest black pearl is the deep purplish green colored pearl. From the 1960s, black pearls have been cultured due to which there is a drastic fall in their price.
To make a pearl, the pearl farmer slits the mantle of the oyster and introduces a small irritant into the shell. The oyster then secretes nacre on that foreign particle till a pearl is formed. Unlike natural pearls that take 6 years to form, these cultured pearls are created only in a year.
Pearl diving or fishing has become a commercial activity today and just to obtain a single pearl hundreds of oysters are killed. Owing to this fact, the number of oysters has dwindled and natural pearl production has reduced, paving way for the cultured variety.