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Pearls are also obtained in commercial quantities from some species of the closely related winged oyster genus Pteria. Pearls are also produced from freshwater mussel species unrelated to pearl oysters. These freshwater species include Hyriopsis cumingii, Hyriopsis schlegelii, and a hybrid of the two species. At danger from the large demand for ...
This species is commonly farmed and harvested for pearls, and there is general consensus that the quality of pearls from Pinctada margaritifera is the highest quality out of all the pearl oysters. Pearls form when a parasite or other irritant enters into the oyster and nacre is released by the oyster to coat the object, eventually creating a ...
A black pearl and a shell of the black-lipped pearl oyster. The iridescent colors originate from nacre layers. All shelled mollusks can, by natural processes, produce some kind of "pearl" when an irritating microscopic object becomes trapped within its mantle folds, but the great majority of these "pearls" are not valued as gemstones.
Tahitian pearl sizes in different colors. The culturing process of a Tahitian pearl involves a grafter, who inserts a bead made from a mollusk shell into the gonad, or reproductive organ, of the mature Pinctada margaritifera mollusk. It takes two years for an oyster to mature enough to begin producing pearls.
There are two different color varieties: the Gold-lipped oyster and the Silver-lipped oyster. These bivalves are the largest pearl oysters in the world. They have a very strong inner shell layer composed of nacre, also known as "mother of pearl" and are important to the cultured pearl industry as they are cultivated to produce South Sea pearls.
The largest pearl-bearing oyster is the marine Pinctada maxima, which is roughly the size of a dinner plate. Not all individual oysters produce pearls. In nature, pearl oysters produce pearls by covering a minute invasive object with nacre. Over the years, the irritating object is covered with enough layers of nacre to become a pearl.
The shell has a rounded outline, with a nearly equal height and width. Oyster shells are usually oval or pear-shaped, but will vary widely in form depending on what they attach to. Oysters have a strong inner shell layer composed of nacre, also known as "mother of pearl". An oyster can filter 1.3 gallons of water per hour.
By the 1840s, the export of the shells was as valuable as the pearls extracted from them; the nacreous shells were used to make mother-of-pearl buttons for clothing. In 1874, compressed air diving equipment made harvesting the oysters easier. By the early 1900s, some 200,000 to 500,000 oysters were being harvested annually. [10]