The English word pearl comes from the French perle, originally from the Latin diminutive of perna leg, ham, leg-of-mutton shaped bivalve.
What is a pearl? – A pearl is a hard object produced within the soft tissue (specifically the mantle) of a living shelled mollusk. Just like the shell of a mollusk, a pearl is made up of calcium carbonate in minute crystalline form, which has been deposited in concentric layers. The ideal pearl is perfectly round and smooth, but many other shapes of pearls (baroque pearls) occur. The finest quality natural pearls have been highly valued as gemstones and objects of beauty for many centuries, and because of this, the word pearl has become a metaphor for something very rare, fine, admirable, and valuable.
Where do they come from? – The most valuable pearls occur spontaneously in the wild, but they are extremely rare. These wild pearls are referred to as natural pearls. Cultured or farmed pearls from pearl oysters and freshwater mussels make up the majority of those that are currently sold. Imitation or fake pearls are also widely sold in inexpensive jewelry, but the quality of their iridescence is usually very poor, and generally speaking, artificial pearls are easily distinguished from genuine pearls. Pearls have been harvested and cultivated primarily for use in jewelry, but in the past they were also stitched onto lavish clothing. Pearls have also been crushed and used in cosmetics, medicines, and in paint formulations.
How are pearls formed? – The difference between wild and cultured pearls focuses on whether the pearl was created spontaneously by nature – without human intervention – or with human aid. Pearls are formed inside the shell of certain mollusks as a defense mechanism against a potentially threatening irritant such as a parasite inside its shell, or an attack from outside, injuring the mantle tissue. The mollusk creates a pearl sac to seal off the irritation. Almost any shelled mollusk can, by natural processes, produce some kind of “pearl” when an irritating microscopic object becomes trapped within the mollusk’s mantle folds, but the great majority of these “pearls” are not valued as gemstones. Nacreous pearls, the best-known and most commercially-significant pearls, are primarily produced by two groups of molluscan bivalves or clams. A nacreous pearl is made from layers of nacre, by the same living process as is used in the secretion of the mother of pearl which lines the shell.
A “natural pearl” or “wild pearl” is one that forms without any human intervention at all, in the wild, and is very rare. Many hundreds of pearl oysters or pearl mussels have to be gathered and opened, and thus killed, in order to find even one wild pearl, and for many centuries that was the only way pearls were obtained. This was the main reason why pearls fetched such extraordinary prices in the past. A cultured pearlis formed in a pearl farm, using human intervention as well as natural processes.
What is the best way to clean my pearls? – Rub pearls individually with a soft, clean cloth that has been dampened with a solution of two cups warm water and a few drops of a mild detergent. Pearls should not be soaked because it can cause the string to stretch. Air-dry the pearls overnight. Pearls should be worn after cosmetics and hair spray are applied — these can discolor pearls. Jewelry should be worn frequently for greater luster. The pearls absorbs the skin’s natural oils. They get a nice shine the more they are worn. Avoid ultrasonic gem cleaners since they can cause your pearls to crack.Some information from: http://en.wikipedia.org/wiki/Pearl