The majority of Oris watches have a sapphire crystal on the dial side. On some models, the back glass is also made of sapphire.
With a Mohs hardness of 9, sapphire crystal is the hardest of all crystals. It is made of synthetically produced sapphire and is highly scratch-resistant. Only a diamond with a Mohs hardness of 10 is harder. Sapphire crystal is more impact-sensitive than mineral crystal.
In order to achieve a clearer view of the dial, sapphire crystals are often anti-reflective on the inside.