Actually sapphire is NOT "the hardest natural substance after diamond". Moissanite seems to be. It has a hardness of 9.5/10 (sapphire: 9/10) and occurs naturall

Actually sapphire is NOT "the hardest natural substance after diamond". Moissanite seems to be. It has a hardness of 9.5/10 (sapphire: 9/10) and occurs naturally, but can also be produced technically.