The lab-grown diamond industry is booming. A 2.7-carat stone goes for about $2,800, compared to a natural diamond that sells for $30,000-$45,000.

Cost is just one reason there's more interest in lab-grown stones.

“There are good structures in place for proper ethical production of lab-grown diamonds, particularly where green energy is used in their manufacture,” said David Brough, editor of Jewellery Outlook.

A diamond research firm shows over the last two years alone, the market has expanded by 4 percent. But experts say it's important that sellers are always making it clear when a diamond is not natural.

“So that could actually lead to losing money and also losing your reputation if you ever get it wrong,” said Brough.

The U.K.-based National Association of Jewellers published a set of guidelines for sellers to follow, including a cheat sheet for consumers to better understand the diamond industry’s terminology.