Cultured freshwater pearls

Quality of cultured freshwater pearls is evaluated through a grading system of a series of A values, based on luster, shape, surface, colour and matching.

The industry attempted a comeback with a mussel hybrid (Hyriopsis schlegeli/Hyriopsis cumingi) in Lake Kasumigaura in the last decade, but this venture also met with failure, with production ceasing in 2006.

The grafting process begins by choosing a suitable donor mussel and cutting a strip of tissue from the mantle.

Unlike saltwater bead nucleation, this process is not considered difficult, and technicians need only minimum training to perform the operation.

The technician creates small incisions on the upper valve, and inserts the tissue piece.

A small twist of the tissue upon insertion is believed to create a higher ratio of round pearls.