Yes, even sapphire glass can be scratched. Sapphire ranks as a 9 on a hardness scale ranging from 1 to 10. Only diamonds, ranking at 10, are harder. This means that sapphire glass can be scratched by a diamond or by an equally hard material. Concrete, for example, contains corundum, which also ranks as a 9 on the hardness scale, meaning it can also cause damage to sapphire glass.