What causes Color in South Sea Cultured Pearls?
Colour in cultured pearls has many causes, namely organic pigments and the chemistry related to the water reservoir where the pearl shell is grown (sea water and freshwater have different manganese (Mn) concentrations with impact on nacre's colours). The pearl mollusc species is, of course, one of the most important factors in this process, specially the donor specimen that provides the mantle tissue that is inserted in the gonads or mantle (depending on the culturing method) of a productive pearl mollusc for the formation of the cultured pearl sac. Understanding colour mechanisms is critical in the laboratory to determine if the colour of a pearl is natural or a resulto or a treatment (e.g. dyeing, heat, bleaching).