Types of Pearls

A pearl is a gem that forms within the tissues of a mollusk, primarily oysters and mussels. Pearls form when mollusks deposit nacre around an irritant in concentric layers. There are many different types of pearls.

Natural Pearls

Natural pearls occur when a grain of sand or a piece of coral naturally enters a wild mollusk, primarily oysters. Natural pearls are entirely nacre, and can take up to 10 years for a 6mm natural pearl to form. Natural pearls are the rarest type of pearls and are mostly found in older jewelry.

Cultured Pearls

Cultured pearls form around an irritant that was artificially inserted into an oyster. Most pearls sold today are cultured pearl varieties.

Saltwater Cultured Pearls

This type of pearl forms in oysters that are farmed in saltwater. Each oyster forms only one pearl, and it takes over 2 1/2 years to harvest. These factors make saltwater pearls more expensive than freshwater pearls. The main suppliers of saltwater pearls include Australia, Thailand, Burma, South East Asia, Thailand and Indonesia. Saltwater pearls are generally cream, white, gold, yellow, rose, silver or black.

Freshwater Cultured Pearls

These pearls form in mussels that are farmed in freshwater. The oysters and the irritants used to create freshwater pearls are smaller than those for saltwater pearls. The cultivating techniques generally produce at least 20 pearls per oyster, and it only takes 1 1/2 to 2 years to harvest. China and Japan are the main global suppliers of freshwater cultured pearls. While the United States (US) boasts several cultivation centers along the Mississippi River, they primarily supply the domestic market.

AustralianSouthSea Pearls

Australian South Sea Pearls are rare, cultured pearls known for their natural beauty and size, which ranges from 8mm to 18mm. These pearls are naturally a pink, blue, silver, gold or white color.

Japanese Cultured Pearls

Japanese cultured pearls include the popular Akoya pearls. Akoya pearls are usually round and typically smaller than other types of cultured pearls. Akoya pearls are available in cream and white colors with pink or silver undertones.

Keshi Pearls

Keshi pearls, often called poppy seed pearls, are a byproduct of the culturing process. These seedless pearls form when tiny bits of debris enter the oyster during harvesting and the oyster covers it with nacre. These pearls are small and their shapes vary widely since no nucleus guides the shaping of the pearl. Keshi pearls can form in either freshwater or saltwater pearls. Keshi pearls are rare today since pearl farms now x-ray oysters to determine whether a pearl contains a nucleus.

Mabe Pearls

Mabe pearls form against the inner part of an oyster's shell instead of within the soft tissue. While mabes occasionally appear in natural pearls, it is far more common in cultured pearls. Mabe pearls occur when a small plastic dome is inserted inside of an oyster and it covers it with nacre. These half pearls have a rainbow-colored iridescence and are commonly used in earrings and ringed.

References

http://www.jsbeads.com/Fresh-Water-Pearls/Pearl-Types.asp

http://www.costellos.com.au/pearls/types.html

http://www.absolutepearls.co.uk/popular-pearls.php

http://www.pearls.com/Types_Of_Pearls1.asp