Man-Made Diamonds Grow, but Not on Watch Brands Production has increased sharply in recent years, yet just two new timepieces include the gems. The Barillet Superpunk Diamants Lab Experience collection uses lab-grown diamonds. By Nazanin Lankarani April 6, 2021, 5:02 a.m. ET Many watch brands are using alternate materials like recycled plastics and cardboard packaging. But only recently have a couple of brands turned to decorative gem-quality diamonds produced in a laboratory, a change that has been a long time coming. In February, the French brand Barillet used lab-grown diamonds to bring a touch of pizazz to its Superpunk Diamants Lab Experience collection. And last September, the Japanese brand Citizen included them in its L Ambiluna women’s watches.