The operation that involves operating an oyster or mussel so as to induce nacre secretion and the growth of a cultured pearl is termed grafting. It is also called nucleation or seeding. This is a vital step in the cultured pearl farming process. This step requires great skill and hygienic conditions. The oyster is operated and a nucleus is inserted together with a piece of donor mantle tissue (the ‘saibo’, also called graft) into a part of the oyster called the pearl pocket. This operation is carried out by an experienced grafting technician. A critical step, it is one of the main factors that determine the quality of pearls that is subsequently produced.
In some cases, the implanted nucleus can be rejected by the oyster or falls out of the ‘pearl pocket’. If this happens, it can lead to the growth of beadless (without a nucleus) cultured pearls, also called Keshis in the trade. These types of pearls exist as by-products in all types of marine pearl oysters. Beadless cultured pearls are also increasingly been produced from the beginning now.