Sapphire crystal, on the other hand, barely needs  an introduction. It was first used for watches, by Jaeger-LeCoultre, in the Duoplan in 1929. Most modern watches utilize sapphire crystals for its fantastic properties: It’s strong, clear,  and most importantly, virtually scratch-proof, at least when compared with acrylic crystals. But, unlike acrylic crystals such as Hesalite, scratches cannot be easily polished out should they occur, and sometimes the entire crystal has to be replaced. Some Hesalite Speedmaster owners find the ceremonial aspect of polishing out scratches charming, and there’s a certain luster to a Hesalite crystal that simply isn’t present on the sapphire model. It’s a softer, more gentle look. In certain angles, the curvature of the Hesalite distorts the seconds track around the edge of the dial in a way that isn’t found on most modern watches.