Mother of pearl, like coral and jet is an organic gemstone. All jewellery that originates from a living creature, plant or other living organism is classified as organic. Mother of pearl is in fact the common name for iridescent nacre, a blend of minerals secreted by oysters and other mollusks and deposited inside their shells. It is used by the mollusk for coating and protecting their bodies from parasites and damaging detritus. Pearls are made by the nacre that forms around the foreign body inside the mollusk.
Natural mother of pearl can be found in both white and black, and may be artificially tinted to almost any colour. It is often used in thin laminated sheet form, and is then cut into artistic shapes. Apart from designer jewellery, it is also used for shirt buttons (although plastic has largely replaced its use, the popular Lacoste brand of Polo shirts still has mother of pearl buttons), key touches and various decorations on musical instruments such as saxophones and trumpets and to clad porcelain sinks.
Among the chief sources are the pearl oyster, found in warm and tropical seas, largely in Asia, freshwater pearl mussels, found in many rivers of the United States, Europe, and Asia and the abalone of California, Japan