The triangle shell oyster, or the hyriopsis cumingi, is the most common kind of Chinese freshwater mussels. These mussels are both hatchery-bred as well as collected in the wild by the Chinese. They are not nucleated until they are 6 to 7 months old, and about 5cm to 6cm in diameter. Each freshwater mussel can be implanted with 40 to 50 nuclei. Their pearl growth period is anywhere between 2 to 6 years and they can be nucleated 1 or 2 times.
Although China, Japan, and the US all produce freshwater cultured pearls, China dominates the market. The Chinese produce a massive volume of freshwater pearls every year. The exact number of freshwater pearls produced in china is unknown, but experts estimate that they produce 10 times the amount of all other freshwater countries combined.
Most farms for pearl jewelry in China are within 300 miles of Shanghai. Lake Taihu, where freshwater pearl culture began, is still used as a pearl farm site today. There are countless small, family run pearl farms all over the countryside in China, as well as large corporation owned operations. The Chinese freshwater pearl industry is indeed the largest pearl industry in the world.