Cultured pearls are harvested from pearl farms after a nucleation period of 8 months to 6 years. Akoya pearls are typically cultured from 8 months to 2 years, while freshwater pearls, South Sea pearls and Tahitian pearls are cultured from 2-6 years.
Pearls are almost universally harvested in winter. During these colder months the metabolism of the host oyster has decreased, slowing the nacre deposits around the pearl. While slower nacre deposits are reflected in less growth during these colder months, it also enhances the outer layers of the cultured pearls' nacre.
When the actual harvest begins the pearls are brought to shore from their mooring positions.The pearls are then opened individually and the pearl or pearls extracted. In the case of akoya oysters and freshwater mussels the shell and meat is discarded or used for another purpose. South Sea and Tahitian oysters, however, are harvested in much the same fashion as the nucleation.These oysters are opened very slightly, the pearl is extracted and another nucleus is placed into the preformed pearl sac.This oyster than goes through another recovery period and is placed back into the sea to grow another pearl.
After all the pearls are harvested they are then cleaned of debris and polished to bring out a higher lustre. After the pearls have been cleaned and polished they are then sorted by quality and size categories. Many of these pearls may then go through further treatment depending on the type of pearl and the factory preparing the finished goods.The pearls may be bleached, heat treated and pinked (soaked in red dye to enhance the pink coloration of the pearls).
A good harvest is determined by the number of marketable pearls produced in relation to the number of oysters which had been nucleated. Of these marketable pearls the more pearls that are considered high-quality have a direct influence on the success of the enterprise. On average, only half of the pearls will be marketable and less than 10% of these will be considered top-quality.