Yet in spite of their history and commercial value, we still don’t fully understand how pearls form ... shell. Several layers grow at the same time, creating terraces that can be seen on a pearl ...

When pearls are cultured commercially an irritant is manually inserted into a mollusc to promote the production of mother-of-pearl. Nacre can form naturally around almost any irritant that gets inside ...

The interior shell, called the nacre, of most oysters is usually a glossy white or silver but the Tahitian black-lipped oyster features a thick band of black. If the pearl forms near that band ...

Pearls are the result of a mollusc's reaction to irritants such as parasites that enter its shell. Although model pearls ... and in turn became a unique pearl. Pearls take a long time to form. Andreia ...