Saltwater pearls from the Akoya oyster (Pinctada fucata martensii), which are usually cultured.  These pearls are typically roundish, and their natural body colors normally range from light pink, to white, to yelowish.  Even though they are often called Japanese pearls, they can also be found in oyster outside Japan.  China has become the major producer of Akoya pearls less than 7mm in size.