Where They Have Been Cultured?
Freshwater pearls are cultured in mussels grown in freshwater environment, like lakes or rivers. Most freshwater pearls come from China.
Saltwater pearls are cultured in mussels grown in ocean. The three most common types of saltwater pearls are Akoya pearls, Tahitian pearls and South Sea pearls.
Nucleation
Freshwater pearls are mantle nucleated, in other words a piece of the mantle of a sacrificed mussel is inserted into the receiving freshwater mussels where the ‘nacre’ forms around it to produce the pearl. Freshwater pearls are solid pearl.
Saltwater pearls are bead nucleated. A small round bead is inserted to stimulate nacre production (nacre is the material that creates the pearl). The rounded shape of the bead helps to produce the classic round pearl shape.
Size, Shape & Color
Most freshwater pearls range from 3 mm to 12 mm and are usually smaller then saltwater pearls. Some saltwater pearls range from 8 to 18 mm or larger.
Most freshwater pearls are mostly round to off round, or rice-shaped to baroque. Saltwater pearls are generally round in shape because of bead nucleated and the shine is more brilliant than freshwater pearl.
Freshwater cultured pearls can be created in a spectrum of colors. Many popular colors, white, pink, orange, and other pastels, can be achieved through natural means. Saltwater water pearls, such as south sea pearls, have white, silver, cream and golden color.