A century ago, pearls were harvested in the wild from ocean floors and river bottoms. It was extremely difficult to find a naturally formed round pearls.
Today, almost all pearls used for jewelry are cultured pearls. Large quantity of round pearls are produced by using pearl culturing technique first developed by Tatsuhei Mise and Tokichi Nishikawa in Japan.
Nishikawa was the one granted the patent in 1916. The technology was commercially used to akoya pearl culturing in Japan in 1916. Mise's brother was the first one to produce commercial akoya pearls. Nishikawa married the daughter of Mikimoto. Mikimoto used the technology after the patent expired in 1935.
Mitsubishi first used the technology to successfully produce a cultured South Sea pearl in 1931, but the project was discontinued at the beginning of WWII before significant productions of pearls were achieved. After WWII, the South Sea pearl projects was re-started in Burma, Kuri Bay and Port Essington in Australia.
Pearl farmers began culturing freshwater pearls using the pearl mussels native to Lake Biwa in middle of 1910s. Because of tremendous success, "Biwa pearls" was at one time nearly synonymous with freshwater pearls.
The original Japanese akoya pearls were produced by a species of small oysters, Pinctada fucata martensii, which are no bigger than 6 to 7 cm in size. Today a hybrid oyster (a cross between the original Japanese oyster and Pinctada chemnitzii of China) is used in both Japan and China in akoya pearls culturing.
Today, China supplied over %95 of freshwater pearls and %80 of akoya pearls in the world pearl market. Japan is no longer produce smaller akoya pearls (less than 8mm). Japan is now importing the majority of Chinese akoya pearls to process and re-label them as product of Japan to export..