Tahitian pearls are the only naturally occurring black pearls in the world. These pearls are created by the black-lipped pinctada margaritifera oysters found in the waters of French Polynesia. They are considered the second most valuable pearls in the world, typically treasured for their exotic colors and extraordinary luster, caused in part by their unique nacre thickness. By French Polynesian law, the minimum nacre thickness allowed for the export of Tahitian pearls is 0.8mm, which is considered quite thick in the pearl and jewelry industry. While Tahitian pearls are often characterized by their iconic black color, they actually have the greatest natural variation of exotic colors of all pearls. Some examples are peacock green, silver green, blue, and eggplant.