 It has always been a generic term, not a trademark, and its application to freshwater pearls by the Chinese is based on visual similarity that is quite close.Chinese use of "keshi" for freshwater pearls is generally limited to those from a second (or subsequent) harvest.These differ considerably from the plump, full shapes of first-harvest freshwater pearls, which grow during a young mussel's growth period, when nacre production is at its peak.