What are they? Lab-grown diamonds have always been viewed as a possibly formidable competitor to natural (mined) diamonds. Unlike simulants, the stones are diamonds—chemically, physically, and visually—but they have been produced in a lab rather than from a mine. For a long time, companies could manufacture only yellows and other fancy colors, rather than colorless gems, because “white” gems often cost too much to produce. Now, they hope to increase their production of colorless gems.Are they detectable? While most jewelers and dealers cannot tell these diamonds apart visually, they ar