|What is a Pearl?|
Most Pearls are mainly made of Nacre. Nacre is actually a mixture of many inorganic and organic substances, thus, Pearls are not a pure substance (like a diamond, made up of Carbon), but instead, they are made from a compound that embodies purity. The reason for a pearl's unique look (when it does indeed display the much prized orient/iridescence/chroma effect) is due to the way light is affected when it strikes the pearl's surface. Light is refracted and diffracted, thus producing the pearl's unique beauty. To read more information on the subject, visit our "Orient & Overtones" information.
Chemically speaking, pearls are made of Calcium Carbonate, Protein and Water. Their main source of Calcium Carbonate in a pearl is in the way of Aragonite, which has flat hexagonal shaped crystals. These crystals are bound by means of a protein known as Conchiolin, and this protein has a fair amount of water in it. Trapped between the crystals and the protein are several trace elements, mostly metallic (color giving) ions. Some of the pearl's conchiolin contains porphyrins that are responsible for a pearl's coloration as well. If a species of pearl oyster (or mussel) does not secrete these natural pigments, its pearl will have a lighter coloration.
A Sea of Cortez Pearl contains unique porphyrins that enable this pearl to glow "red" (light pink to red blood) under a long wave ultraviolet lamp. No other pearl in the world does this, thus it serves as an identifying attribute. The image above displays several varieties of cultured pearls under normal light situation, but the image below displays the same pearls under a long-wave Ultraviolet (UV) light. It is very easy to distinguish the pearl produced by the Rainbow Lip Pearl Oyster (Pteria sterna) because they display a light pink to blood-red coloration. Not even the pearl from the Mexican Black-Lip Oyster (Pinctada mazatlanica) displays this unique fluorescence, and this is a species that lives in the same environment as the Rainbow-Lip Oyster.