The main differences between cultured freshwater pearls and akoya pearls are the culturing process, the nucleus, the shape and the value.
Freshwater pearls are mantle-tissue nucleated by inserting a tiny piece of mantle tissue directly into mantle tissue of a freshwater mussel, whereas akoya pearls are bead-nucleated by inserting a mother-of-pearl bead and a piece of mantle tissue into the gonad of akoya oyster. Therefore, freshwater pearl is composed of almost solid nacre. Akoya pearls may only have .1 to 2 mm nacre over a bead nucleus.
Freshwater mussel can be inserted 12 to 16 times per valve, producing up to 32 pearls. An akoya oyster can generally be inserted 1 to 2 times with a shell bead and tissue piece into its gonad.
Freshwater pearls are much easier to farm than akoya pearls. Their successful harvesting rate is much higher than that of akoya pearls. The implanting operation and training are also much easier with a freshwater mussel.
Akoya pearls have higher quality attributes than freshwater pearls. Freshwater pearls are rarely round, whereas akoya pearls are generally round. Freshwater pearls do not have the good luster of akoya pearls. Although harvested freshwater pearls have solid nacre, and akoya pearls may only have only .1 to 2mm of nacre over a bead-nucleus, akoya pearls are generally considered more valuable because of their excellent luster, consistently round shape, rarity and popularity.