The pearl is made in the mantel tissue of the oyster. It is not a normal behavior of the oyster to create a pearl, it is more about protection against something intruding. If something succeeds to come in, the oyster tries to push it out. If this don`t work the oyster encapsulate the intruder with pearl secret, pearl substance. The oyster weaves layers of layers around the intruder and a pearl is made. This natural behavior is used when to “cultivate” pearls. Japan is the world leading pearl cultivator.
There are two kinds of natural pearls that are not cultivated:
1) Oriental pearls, from salt water
2) Natural sweet water pearls, from sweet water
There are three main groups of cultivated pearls:
1) Pearls cultivated in the Akoya mussel
2) Pearls cultivated in the South Sea
3) Pearls cultivated in sweet water
The difference between natural and cultivated salt water pearls is that the natural pearl consists mostly of pearl substance whereas the cultivated pearl has a ball of mother-of-pearl in the middle.
One of the oldest, most famous pearl necklaces is from app. 4000 years B.C.
In a holy text from India from app. 500 years B.C. it´s written that pearls gives you a long and happy life.
All ready in the 13th century the Chinese started to cultivate Buddha figures in oysters. They put in figures of clay or tree between the oyster shell and the mantel. After a while they opened the oyster and hopefully the figure was then covered with pearl substance.
Two Japanese, Mise and Nishigawa, was independent of each other, able to find the technique to cultivate round pearls. 1907 they both applied for a patent. This method is still used today.
The pearl cultivation in Japan started on a bigger scale in the beginning of 1920.