By Ashley Bailey
, Tuesday, November 10, 2009
Natural pearls are created without any intervention from man when a tiny irritant finds its way into a mollusk. This causes the animal to secrete a substance to encapsulate the intruder in order to reduce the irritation. The result can be quite magical as the process continues over time to produce a lustrous spherical gem. Natural pearls of any significant size are extremely rare and are almost nonexistent in the market today.
Cultured pearls are produced by the mollusk in exactly the same way as natural pearls, except that the irritant or nucleus is specially prepared and surgically implanted. Fortunately, the modern industry of pearl cultivation which began in the late 1800's is thriving today, making beautiful pearls both available and affordable. Cultured pearls are produced in a variety of different mollusks in both saltwater and freshwater.
The process of growing a cultured pearl is also referred to as pearl cultivation or pearl "farming" in that large areas of controlled natural waters are utilized for the production of quantities of pearls after carefully planting "seeds" or nuclei in a large number of mollusks. The implantation of nuclei is done in a surgical fashion and the mollusks are nurtured carefully though the growing period. Different varieties of mollusk produce very different types of pearls and are cultivated using a wide variety of techniques. Saltwater pearls are nucleated with polished round beads made from a freshwater clam found in certain American rivers.
Like traditional farms, the pearl crop is subject to fluctuations in water and weather conditions and the results of any given harvest are uncertain, and the market fluctuates accordingly.
Types of Cultured Pearls
The most important types of pearls are the Akoya, South Sea, Tahitian Black, and freshwater.
Produced by the Pinctada Fucata oyster, the akoya is cultivated in the seas of Japan and China and yields a high percentage of spherical pearls from 2-9mm. A single Akoya can produce as many as 5 individual pearls in 8-24 months, but can only be nucleated once.
South Sea Pearls
Produced by the Pinctada Maxima oyster, South Sea pearls are grown mainly in Australia, Indonesia and the Phillippines. Two varieties of this oyster, gold lipped and silver lipped, account for the characteristic gold and silver colors of these cultured pearls. Australian pearls grow the biggest and range between 10-15mm, with an average size of 13mm. A South Sea oyster can produce only a single pearl in 18-24 months, but can be nucleated up to 3 times.
Produced by the Pinctada Margaritifera, a black lipped oyster, Tahitian pearls exhibit a variety of unusual colors including the exotic Tahitian Black. They range in size from 8-14mm with an average size of 9.5mm. A Tahitian oyster can produce only a single pearl in 22-26 months, but can be nucleated up to 4 times.
The mollusks that produce freshwater pearls are called mussels and are grown in rivers, lakes and ponds. There are many species of mussels that produce freshwater pearls, but the main producer is Hyriopsis Cumingi. It is called "triangle shell" in its native China, which produces the majority of the world's cultured freshwater pearls. These mussels can produce up to 50 individual pearls and can be nucleated up to two times. Freshwater pearl cultivation is unique in that it involves nucleation with soft tissue rather than a hard bead.
Any material intended to simulate the look of pearls but manufactured entirely by man, usually some form of glass or plastic, is an imitation. "Majorca pearls" are an example of a high-end imitation or simulated pearl, also known as a "faux pearl".