A the end of a process of growth (nearly 2 years) during which the oyster pinctada margaritifera reaches a critical size of 8 cm, it is extracted from the lagoon in order to be grafted. During this short but also delicate operation, a nucleus (a small ball of nacre) and a slice of another oyster's flesh are introduced within the mollusk. The presence of an external corpse makes it secrete nacre all around it. It takes another 18 months of growth in the lagoon to produce an authentic black pearl.