South Sea Pearls South Sea Pearls are some of the rarest, most valuable pearls available. They have a satiny luster and range from 9mm to 20mm in size making them the largest pearls available. South Sea pearls are harvested off the coast of northern Australia from the Pinctada Maxima oyster. As its name implies, it is one of the largest pearl producing oysters in the world. Golden South Sea pearls, which are produced by the same species of oyster, are harvested off the coast of Indonesia.