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Pearls have long been a sought after gemstone and like all other precious stones they are judged for specific qualities they possess which in the case of a pearl is their luster, size, surface quality, iridescence and orientation. The luster is determined by the amount of reflection, refraction and diffraction of light from the translucent onion layers as the pearl is built up; iridescence is determined by how much these "onion" layers overlap each other which makes the rays of light break up as they try to pass through them.
Pearls are very valuable and have been farmed for thousands of years with much of the value being ascribed to the enormous amount of human labor required and not to mention the danger inherent in bringing them to shore - pearl's had to be found by divers going to the sea bed and individually hunting for them.
Naturally formed pearls come from all mollusks that use the process of creating a pearl to seal off an intruding piece of matter such as a grain of sand (though this is rare in practice as it much more likely to be foreign organic matter or parasites). This is part of the mollusks natural defense mechanism and operates involuntarily. Cultured pearls are made by the intervention of man and are created essentially as part of a production process which deliberately introduces the foreign body around which the pearl will be formed.
The mollusk deposits a mineral, aragonite and sometimes with a mixture of calcite around the foreign body and the entire concretion is held together by a glue-like substance known as conchiolin. This is built up and forms a layered structure which seals off the foreign intruder from the body of the animal and the combination of aragonite and conchiolin is known as "nacre" which in turn makes up "mother of pearl".
Natural pearls are almost made entirely of conchiolin and calcium carbonate; they come in a variety of shapes and sizes with completely round pearls being a rarity in nature. Cultured pearls are far more common and they are usually "pre-formed" with a bead inserted into the mollusk which they places a thin shell of nacre around the foreign object and therefore is not completely made up of pearl material. Natural pearls are also capable of being dyed different colors whereas natural pearls are a light, pearly white color.
For cultured pearls which are completely organic in that there is no bead around which the mollusks lays a shell of nacre, it requires an X-ray to differentiate it from a natural pearl. A cultured pearl will not show the concentric spheres of a naturally occurring pearl and is usually also not completely solid to the core.
There is also a further distinction to be made between saltwater and freshwater pearls, the former being the more sought after of the two. They do look very alike but freshwater pearls originate from the Unionidae family of freshwater mussels which inhabit lakes and rivers and are distributed widely geographically in both hot and cold climates. Saltwater pearls originate from the Pteridae family of oysters which are ocean dwellers and today are typically raised in protected lagoons and atolls in warm tropical climates.
About the Author
Lawrence Reaves for DanforthDiamond.com, an authority on engagement rings
and fine jewelry. Danforth Diamond provides wisdom and advice to help you choose the right engagement ring at the best price. Visit DanforthDiamond.com or call 877.404.RING. Looking for pearl jewelry
for your wedding? Visit MuseumWayPearls.com
