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