Pearls have been known to mankind since the beginning of civilization. The success of the pearl culture industry depends on the high rate of production of quality pearls. The value of a pearl depends on its quality, size, shape, colour and lustre. Being a product of biological origin, individual variations are bound to occur in each pearl. The secretion of the mantle or the pearl-sac, which leads to the formation of the pearl, may be organic or inorganic or both in origin, with unpredictable and subtle variations in structure and composition. The final product may range from the finest to the...