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
Pearl of Csaba Pearl of Csaba Pearl of Csaba ("Csabagyöngye" in Hungarian) is a white variety of grape. It was created in 1904 by the Hungarian viticulturalist Adolf Stark, presumably by crossing Madeleine Angevine × Muscat Courtillier (= Muscat Précoce de Saumur). Some sources instead state the parent varieties as Bronner x Muscat Ottonel, but this is seen as less likely. The variety's name was taken from the city Békéscsaba, which is also called "Csaba" for short. Pearl of Csaba is primarily used as a table grape. Worldwide cultivation is estimated to be around , and it is primarily found in Romania, Hungary