South Sea Pearls (from Australia, Indonesia etc) are primarily white, but there are some spectacular golden pearls. 🙂 By contrast, Tahitian pearls (also in the Cook Islands) range from silver, champagne, grey to black - no pure white. In the Abrolhos Islands of Western Australia a company is farming the Tahitian pearl oysters (Pinctada margaritifera) but they can't achieve the spectacular black pearls. Theirs are grey. In discussing this with a pearl 'farmer' I asked if it was the temperature of the water that makes the difference, but he said it is the organisms in the water.