Cultured pearls are harvested by pearl farmers. People learnt about this culturing technique to create pearls in the beginning of the twentieth century. One of the most famous inventors was a man called Kokichi Mikimoto, who is known as the father of Akoya pearls.
You can find Mikimoto pearls on the website pearlsonly.co.uk too.
To start pearl cultivation process, a pearl technician will introduce certain foreign object e.g. a tissue or mother-of-the-pearl bead into a tiny opening made inside the gonad of host mollusc.
The automatic reaction takes place on the mollusc and a pearl sac grows around the irritant that start coating it with nacre layer to smooth it. Cultured pearls can either be created in saltwater or freshwater in different kinds of molluscs.
Cultured saltwater pearls
These pearls are usually cultivated in countries China and Japan. Black Tahitian pearls come from French Polynesia. In Philippine and Australia, golden or white pearls are created.
A round shell-bead nucleus and a tiny tissue of 1mm slice from another oyster will be inserted into the gonad of oyster which forms the base for the oyster for forming pearl sac that eventually starts layering crystalline nacre in layers, almost like an onion.
By 18 months, it is possible to harvest saltwater, but longer the pearls can be left inside the oyster for acquiring thicker nacre layers, the better will be the quality.
Following are the few other countries which are known for producing these cultured saltwater pearls:
Cultured freshwater pearls
Freshwater pearls start by inserting few tiny pieces of mantle tissue inside the mussel. Around 25 insertions are made on shell’s each side. Freshwater pearl can produce more pearls as compared to their saltwater cousins.
Each of the mussels may produce a wide variation of natural colours ranging from few colours like lavender to pink, bright silver white, peach, deeper creamy/ivory shades.
The mussel will start forming pearl sacs on each irritant. After about 2 years, pearls are harvested.
The technology for creating freshwater pearl is constantly changing. You can find new and few unique pearl varieties are making their debuts at various gem shows.