Cultured pearls are made in much the same way as natural pearls by utilizing a technique known as grafting. The grafting technique consists of introducing a perfectly round nucleus, fashioned from the shell of a mussel, into the gonad of an oyster. A small piece of mantle from another oyster is inserted along with the graft. The cells from the sacrificed oyster develop around the implanted nucleus thus forming a pearl sack which, once closed, will secrete pearl material. Before undergoing this grafting process the oyster submits to a fast for several days in order to slow down its metabolism which decreases the risk of rejection.
Many people still make the mistake of believing the cultured pearls are imitations or faux pearls.
In other words, man plays the part of nature by introducing the irritant or the nucleus into the oyster and then steps aside to allow nature to create its miracle.