TiC Can be a form of very challenging ceramic, and it can even be extra scratch-resistant than sapphire having a Mohs hardness rating up to nine.five. The bezel can be topped with sapphire, supplying as much protection as feasible towards the micro gasoline tubes that sort the markers. 1844: Adolphe https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/