Till the 19th Century the only pearls known to man were natural pearls, pearls that accidentally formed in nature. Diving for natural pearls was risky and expensive and often resulted in poor results. Only very few oysters produced a gem quality pearl. This made natural pearls extremely rare and valuable, allowing only royalty and the truly wealthy to enjoy natural pearls.
While some cultures had been able to artificially simulate freshwater mollusks into producing pearls, these were generally hemispherical mabes, rather than round pearls. This all changed in the late 19th century with the efforts of 3 Japanese men.
Today the most famous of these men is Kokichi Mikimoto, the son of a noodle maker. He shared a dream with his wife, Ume, to entice oysters to produce round pearls on demand. Unknown to Mikimoto, government biologist Tokichi Nishikawa and carpenter Tatsuhei Mise had already discovered this secret independent of each other. They had both experimented with inserting a piece of oyster epithelial membrane (or lip of mantle tissue) along with a nucleus of shell or metal into the gonad of an oyster. The oyster then secreted layers of nacre around the nucleus to form a pearl.
Mise was the first to be granted a patent in 1907 for his grafting needle, which was discovered by Nishikawa when he went to apply for a similar patent. The two men signed an agreement uniting their common discovery as the Mise-Nishikawa method, the basis of which remains at the heart of pearl culturing.
Mikimoto had some patents of his own, an 1896 one for producing hemispherical pearls or mabes and a 1908 parent for culturing in mantle tissue. In a bid to avoid invalidating them, he went about altering the Mise-Nishikawa method to cover a technique to make round pearls in mantle tissue. This was granted in 1916.
This technique revolutionized the pearl industry as it allowed the reliable, consistent cultivation of large numbers of round and quality pearls. For the first time, good quality and round pearls were affordable and attainable for all. This monumental shift led to the cultured pearl industry replacing the natural pearl one. Today, pearl culturing and farming take place worldwide, involving many different pearl types and oyster species.