Want to Make a Diamond in Just 10 Weeks? Use a Microwave

The 2.62-carat diamond Calvin Mills bought his fiancée in November is a stunner. Pear-shaped and canary-yellow, the gem cost $22,000. A bargain. Mills, the chief executive officer of CMC Technology Consulting in Baton Rouge, La., says he could have spent tens of thousands more on a comparably sized diamond mined out of the earth, but his came from a lab. “I got more diamond for less money,” says the former Southern University football player, who proposed last year at halftime during one of his alma mater’s games at the Superdome in New Orleans.

While man-made gems make up just a fraction of the $80 billion global diamond market, demand is increasing as buyers look for stones that are cheaper—and free of ethical taint. Human-rights groups, with help from Hollywood, have popularized the term “blood diamonds” to call attention to the role diamond mining has played in fueling conflicts in Africa.