Here is some quick info about Pearls. I do a lot of pearl stringing and love working with them....as you can guess! LOL
Pearls are formed when a tiny bit of sand gets trapped inside an oyster. The oyster produces a "nacre" as a defense mechanism that coats the intruder, layer after layer. A pearl is only found naturally in 1 in every 10,000 oysters. Mother of Pearl is the thick nacre that coats the inner shell of the oyster or mollusk. The oyster secretes the nacre from the cells on the mantle tissue to protect itself from parasitic organisms.
Cultured Pearls are formed with human intervention but placing an irritant into an opened mollusk or oyster. They are more affordable and come in smaller sizes but generally don't get bigger than 13mm (except in Baroque shapes). The necklaces/earrings run in the hundreds.
South Sea & Tahitian Pearls are more expensive and come larger in size.
South Seas usually start at 8mm. The 8mm size is considered "baby South Sea" and they can go to 22mm
The necklaces & earrings will run in the many hundreds- thousands.
The colors can be natural or dyed. These are the common colors you can find in nature......
Natural South Sea colors--- White, Silver/Platinum Grayish, Gold
Natural Cultured- White, Peach, Lavender
Natural Tahitian: Black, Gray, Silver with overtones of Pistachio, Eggplant, Peacock, Red, and many more.
Black only naturally occurs in Tahitian pearls