Pearls form within oysters, which live in the sea, and also within freshwater mollusks. Traditionally, most pearls were gathered from saltwater-dwelling oysters in the Persian Gulf, the Red Sea and the coastal waters of India and Japan, although China has harvested freshwater pearls for many centuries.Saltwater pearls tend to be more lustrous* than their freshwater counterparts, thereby increasing their desirability and value.All saltwater pearls produced today are bead-nucleated pearls. Natural pearls are still collected in the Persian Gulf, but the yield is too small to account for any market value, and the pearls collected rarely leave the area.Saltwater pearls are cultured by taking an oyster and prying it open a mere 2-3 centimeters. A technician then uses a special instrument to make a minute incision on the gonad (reproductive organ) of the oyster. A small nucleus is inserted into this hole, and a tiny piece of mantle tissue is placed behind it. The epithileal cells in this mantle tissue grow around the nucleus producing a pearl sac. This is where the pearl grows. This process is the same for all saltwater pearls cultured today.The three most common types of saltwater pearls are Akoya pearls, Tahitian pearls, and South Sea pearls.