Cultured pearls grow inside oysters, which live in lakes and streams all over the world, including Europe and the US. Pearls that are cultured tend to be smaller, but come in a much wider variation of shape and colour. They are also generally cheaper than natural pearls, even if they have the same colour or size. The largest manufacturer of cultured pearls today is China.

Cultured pearls grow and form just like natural pearls, except that the irritant that causes it is placed there by human hands. The oysters or mussels are also raised in a controlled environment, on special farms. Usually, a small piece from another oyster is placed inside, to cause irritation. This causes the oyster to create a shell of nacre around the irritant, to protect itself. After about three to five years, the pearl is ready to be harvested. The longer the pearl stays inside the oyster, the thicker and shinier the layer of nacre will be. One oyster can create new pearls several times, although it normally can’t create pearls bigger than 13 millimetres or so, usually they are about 6-7 mm. However, it can produce as many as twelve pearls at once.