Cultured pearl is calcium carbonate and a fibrous protein called conchiolin. As the nacre builds up in layers of minute aragonite tablets, it fills the growing pearl sac and eventually forms a pearl. Natural pearls are formed by nature, more or less by chance. On the other hand, cultured pearls are human creations formed by inserting a tissue graft from a donor oyster, upon which a pearl sac forms, and the inner side precipitates calcium carbonate, in the form of nacre or "mother-of-pearl". The most popular and effective method for creating cultured pearls are made from the shells of freshwater river mussels
The Black Pearl (play) The Black Pearl (play) The Black Pearl () is a three-act comedy by the 19th-century French playwright Victorien Sardou that was first performed in 1862 in Paris. The play is based upon a story written by Sardou and first published in December 1861 under the title The Medallion. In 1825, in Amsterdam, Messieurs Balthazar and Cornelius sit down to supper during a particularly strong thunderstorm. Balthazar informs Cornelius that he is aware that Cornelius is in love with Christiane, who had been raised by Balthazar’s mother, and is practically his sister. He gives his blessing to a marriage between Cornelius