FRESHWATER PEARLS Freshwater pearls are farmed in freshwater and are grown in mussels. Freshwater pearls are nucleated with a small piece of mantel tissue instead of a bead nucleus which is used in saltwater pearls, which results in a pearl with more nacre, or more pearl, and less core material. Freshwater pearls are typically cheaper because freshwater mussels are larger and can produce up to 40 pearls at a time, whereas saltwater oysters are smaller and can only produce one to five pearls at a time. Freshwater pearls also tend to be off-round since they are not started with a perfectly round bead nucleus.