What's natural pearl ? Natural Pearls: Nature's Treasure A natural pearl is a gem created by a living mollusk, such as an oyster or mussel, without any human intervention. It forms when an irritant, like a grain of sand or a parasite, gets lodged inside the mollusk's body. To protect itself, the mollusk secretes layers of nacre, a substance similar to mother-of-pearl, around the irritant, gradu...