Cultured pearl necklace. Antique and in excellent condition. France. Natural cultured pearls Natural cultured pearls are born as a result of the joint efforts of man and shellfish. If natural pearls are formed completely by chance, it is impossible to predict the shape and size of the pearl in advance. And as a result of cultivation, pearls of a pre-planned shape, size and color are obtained. The process of formation of natural and cultured pearls is almost the same. The difference in the case of the formation of natural pearls is that the foreign body is small parasites, but for the formation of cultured pearls, a person himself begins the process of ripening the pearl, inserting a foreign body into the shell of a mollusk. The quality of cultured pearls depends on the size of the foreign object (usually a ball), the time of “ripening” of the oyster and the thickness of the mother of pearl that covers the ball layer by layer. In a short period of time, a few months, the ball will be covered with a thin layer, while a pearl that grows from one to two years will have a stronger and more durable nacre. X-rays are used to determine the thickness of the pearl layer.