What are cultured freshwater pearls? 

Cultured freshwater pearls are the result of a process in which a small piece of mantle tissue from another mussel or oyster is planted into the mussel. To defend and protect themselves, the mussels begins to encapsulate the foreign object with pearlescent substance. This layer upon layer of pearlescent eventually forms a pearl. The shape can vary and freshwater pearls are usually not as round as saltwater pearls, which gives them their character.

The Biwa pearl

The Biwa pearl is a freshwater pearl that got its name from a lake in Japan called Biwa. The Biwa pearl originally comes from there, but today pearls from the lake are difficult to get hold of. The Biwa pearls sold today are often ordinary freshwater pearls whose shape is similar to the original Biwa pearl.