Saltwater pearls, like freshwater pearls, are formed when an irritant lodges inside the mantle tissue of a mollusk. This causes the mollusk tissue to secrete a substance that eventually develops into a pearl. Unlike freshwater pearls, however, saltwater pearls are formed in a saline environment. Saltwater pearls are also usually more round than freshwater cultured pearls. The most common types of saltwater pearls are cultured saltwater Akoya pearls, South Sea pearls, and Tahitian pearls.
