The largest freshwater processors are located in provinces near Hong Kong, the world pearl marketing center. These processors take the shipments from the pearl farmers and put them through a normal treating process. First they sort the pearl by size, shape, and color. Then they are immersed in a bleach solution in large glass jars. These jars are placed in a room that is flooded with fluorescent light. The pearls remain there for one or two months.
Because the bleaching reduces the luster slightly, afterwards they are mixed with small pieces of vegetable grit, bamboo, wood, or walnut shells and tumbled together. This restores and enhances their luster. Some processors dye their freshwater pearls as well. Though freshwater pearls come in many colors, a black colored freshwater pearl is not as common. Therefore, most of the time when a processor dyes their freshwater pearls, they are dyeing them black. Pink and Lavender freshwater pearls are naturally occuring colors, however other colors can be obtained through the use of radiation on the pearls. These make beautiful pieces of pearl jewelry.