Where Found Pearl Pearl is formed in shellfish as a reactant to an irritant such as a piece of sand. Cultured pearls are created by adding a piece of mussel or shell inside of an oyster of mussel. This then creates a pearl as layers of the inside of the shell grow over the added substance. Pearls are generally white, brown, silver, cream, black or pink depending on the type of shellfish and water.
Natural pearls are the most expensive, followed by cultured pearls.
Fresh water pearls tend to be relatively inexpensive. While pearls generally are thought of as white in color, they also can be found in colors ranging from pink to black. The most common size is about seven millimeters. Care and Treatment Pearls are less durable than most gems. They are sensitive to acids, dryness, and humidity.