Freshwater pearls are cultivated in farms located in freshwater rivers, lakes or ponds. China and the U.S. are the largest producers of cultured freshwater pearls, and the process is still performed mostly by hand.
Cultured freshwater pearls are harvested when they reach 4.0‐14.0mm in size. Freshwater pearls come in a broad variety of colours. Many pearls are bleached to produce white colouration, or dyed to mimic the gray or golden hues of other pearls. Because pearls are so porous, dyes are absorbed deep into the pearl and are relatively permanent. Dyeing of pearls has become widely accepted and dyed pearls achieve a rich depth of colour that generally can't be found in nature.