For centuries, humans have been fascinated by gems because of their rarity, durability, and beauty. Efforts to produce imitation gemstones go far back into history also. Charlatans have long tried to pass off as the real thing minerals that only looked like true gemstones.

The first attempts to produce gemstones in the laboratory occurred in the 1830s. French chemist Marc Gaudin (1804-1880), tried melting chemical compounds that would decompose to produce aluminum oxide, the compound of which rubies are made. Gaudin added a small amount of chromium to impart the characteristic color of the ruby. Although he did not realize it at the time, Gaudin was successful in producing a few tiny crystals of ruby.

In 1904 French scientist Auguste Verneuil (1823-1895) was more successful. Verneuil invented a special furnace for first melting a raw material, such as aluminum oxide, and then allowing it to cool slowly...