Saltwater Cultured Pearls, are farmed in saltwater, and grown in oysters. Only one pearl is grown per oyster. This makes salt-water pearls more expensive than freshwater pearls. Countries known as producer of saltwater pearl are Burma, Indonesia, Thailand, and Philippines in South East Asia; Australia and Tahiti in South Pacific, especially in Tahiti, you'll find the beautiful black pearls.
The Differences. The thickness of the nacre coating Cultured saltwater pearls start with a shell nucleus that is seeded into the oyster. The oysters, over time, secrete a calcium (nacre), which covers this nucleus.
The nacre coating of Japanese Akoya pearls about a half-millimeter. The nacre coating of Tahitian pearls-about 2 to 3 millimeters. South Sea pearls develop the thickest-from 2 to 6 millimeters.
Freshwater pearls are all pearl -- this is a big selling point for freshwater pearls. Because there is no hard nucleus inserted in freshwater pearls, freshwater pearls are almost all nacre.
Only South Sea pearls have a nacre coating as thick as that of freshwater pearls. However, for South Sea pearls to have the same thickness nacre coating of a 10mm freshwater pearl a South Sea pearl should be 18mm in size. You will have to spend a small fortune to have it. It only costs a small fraction of that money to buy a 10mm, top quality freshwater pearl.
