Although originally produced in Japan, over 90% of the world’s freshwater pearls now come from China.
Freshwater pearls are the “odd man out” of cultured pearling as they are not produced by the oceanic Pinctada family of pearl oysters. In fact, they are not produced by an oyster at all. In China, most cultured pearls are farmed in varieties of freshwater mussels such as Hyriopsis and Cristaria. Each shell can produce up to 100 pearls simultaneously.
Most freshwater cultured pearls are nucleated with pieces of mantle tissue – rather than a round nucleus, which is placed directly into a mussel’s mantle to initiate nacre production. Mantle tissue is shell material that is recycled into the formation of new pearls. As with Akoya pearls, freshwater pearls are not marketable for jewelry in their natural state, and require clinical enhancements such as bleaching, coloring, and polishing.
Traditionally, most cultured freshwater pearls grow in irregular shapes from near round to oval, between two and five millimeters in length. With improving production techniques, China now produces round white freshwater pearls up to 12 millimeters that compete with Akoya pearls for size and general appeal. New farming and pearl-enhancement technology has enabled the Chinese to produce more round pearls and a whole new array of colors. Supply is plentiful and quality is highly variable, with the volume of production measured in hundreds and sometimes thousands of tons. Consequently the price of freshwater pearls is much lower than other cultured pearls.