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 trash. Even under the highest possible human control, the quality of cultured pearls cannot control absolutely but can considerably improve through appropriate care in surgery and during farming. Only the size and shape of the cultured pearls are under the control of the pearl culturist. However, the colour and luster, which depend on the secretion of the pearlsac, can also improve to some extent by proper understanding of individual biological and physiological factors as well as the environmental conditions of the culture farms, which influence the formation of pearls.