It is relatively unscratchable and the only substance more scratch resistant is a diamond. ·sapphire crystal (mineral crystals are also available).
Full Gasket Set for BR500 BR550 BR600 BR700 Blowers 7 Pieces Engine Sealing Kit
Sapphire Crystal Rolex 1600 1601 1603 Conversion with Gasket
Watch Sapphire Crystal&Gasket for Longines L4.241/L4.341 La Grande Classique
Watch Sapphire Crystal Gasket for Omega Seamaster Diver 210.30.42
Watch Sapphire Crystal Glass&Gasket for Audemars Piguet 70074 21.5*1.8*0.8mm
Rolex Cyclop Sapphire Crystal & Gasket fit GMT MASTER II 16710 16713 16718 16753