Description
Pearls are made by marine oysters and freshwater mussels as a natural defense against an irritant such as a parasite entering their shell or damage to their fragile body.
The oyster or mussel slowly secretes layers of aragonite and conchiolin, materials that also make up its shell. This creates a material called nacre, also known as mother-of-pearl, which encases the irritant and protects the mollusc from it.
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 shell, creating some very unique and precious pearls.