People in the jewelry trade understand the difference between a diamond simulant and a synthetic diamond. But many consumers do not—and that’s a growing problem.In 2003, Wired writer Joshua Davis hailed the beginning of the lab-grown diamond revolution. Man-made gems, he proclaimed, would be available for as little as $5 a carat. The problem was there weren’t many lab-grown diamonds out there—and 10 years later, there still aren’t. And those that are available sell for a lot more than $5 a carat.Around that time, products labeled “synthetic diamonds” started popping up on eBay. B