Synthetic diamonds have grown in popularity in recent years as a cheaper and arguably more ethical alternative to natural diamonds. Even De Beers, the world’s largest diamond company, entered the synthetic diamond market in 2018 after having pledged for years never to sell man-made diamonds.Lab-grown diamonds possess the same chemical composition and physical characteristics as natural diamonds but unlike mined diamonds, limitless quantities can be produced. A tiny piece of carbon is put into a plasma reactor at very high heat and gradually the tiny crystal grows. After several hundreds of hours, it is big enough to be cut into a polished stone.

“For me, synthetic diamonds have little to do with the world of luxury,” Tiffany boss Alessandro Bogliolo said in an interview at …