11 July 1893 CE
An oyster farmer grows a pearl on purpose.
Read the full sourced page: Mikimoto's First Cultured Pearl
Myth: undefined
Reality: His first cultured pearls, in 1893, were hemispherical. He patented a round-pearl technique in 1916, and commercially viable round harvests came in the 1920s.
The Gem Tray is another reference site by the same author.