What is Freshwater Pearl
Freshwater pearls are the pearls which are produced in pearl farms by the freshwater mussels in freshwater like in ponds, lakes and rivers and the process is called Freshwater Pearl Farming.
Major source of Freshwater Pearls
China is the major source or an undisputed leader in freshwater pearls production. China has harvested the pearls since the 13th century. It holds the monopoly in freshwater pearl industry. In 2006, China produced around 1500 tons of freshwater pearls. The largest marketplace for these freshwater pearls is the world’s pearl trading hub, Hong Kong. The United States was also the major producer of freshwater pearls. But in 19th century, over harvesting and increasing pollution significantly reduced the number of available pearl forming mussels in the US.
Appearance of Freshwater Pearls
Generally, freshwater pearls are not as round as saltwater pearls, and they do not have the same sharp luster and shine as akoya pearls. Freshwater pearls are solid nacre, they are also quite durable, resisting chipping and wear. The entire freshwater pearl cultivation process requires much less advanced surgical skills for full cultivation than ocean pearl cultivation. This helps to make these pearls easier to cultivate and less expensive than other pearls
Culturing Oysters for Freshwater Pearl Farming
Today, pearl farmers find that it’s simpler and more productive to breed their own oysters. Farmers collect high quality oyster eggs and sperm of oysters. The eggs are fertilized with the sperm, creating a new generation of larvae for the oyster farm. The larvae are then allowed to float freely in the water, but under controlled conditions, until they’re a few weeks old. There, they attach themselves to a stable object, such as a rock. Over a few month’s period, the larvae develop into baby oysters. They are then moved into a separate nursery region on the pearl farm. Here they’re tended for around 1-2 years until they grow large to be nucleated.
Nucleation of Freshwater Pearl
Freshwater Pearls differ from other cultured pearls, in that the great majority of them are not bead-nucleated. Mussels are grafted using a piece of mantle tissue only, without the insertion of any bead. The mantle tissue is placed into an incision in the host mussel’s mantle instead of the gonad. Since both sides of the valve can receive grafts, the average freshwater mussel can actually produce up to 32 pearls per culturing cycle.
The technician carefully opens the mussel only about ½ inch wide, in order to avoid injuring the host and cuts a triangular incision in the fleshy mantle tissue, inserting a square piece of mantle tissue from a donor mussel that is approximately 3mm in size, between the Mother-of-Pearl layer and the cell lining.
Once inserted, the donor tissue is strategically shaped and twisted with needles in order to effectively round out the edges to ensure that a physically smooth and comfortably hospitable “pearl sac” is then naturally allowed to be produced and activated.
The mollusks are then returned to their freshwater environment where they are tended for 2-6 years. The resulting pearls are of solid nacre, but without a bead nucleus to guide the growth process the pearls are rarely perfectly round.
Brief History of Japanese Freshwater Pearl Industry
There was a time when Japanese freshwater pearl industry was in boom. Lake Biwa was once world renowned for producing high-quality freshwater pearls produced by the Hyriopsis schlegelii, (Biwa pearly mussel) mussel. However, in the mid 1970’s pearl farming all but came to a halt due to pollution in this lake that was once synonymous with freshwater pearls. The Japanese tried once again to farm freshwater pearls in Lake Kasumigaura in the last decade. The Kasumiga pearl industry had a very short life span, because of the pollution.