A tile’s hardness is not always easy to determine. The Mohs scale or PEI rating is often used to indicate the grade of the material’s hardness. The price of the tile can also help you estimate its hardness: hard tiles normally cost more than the soft ones. The size of your tile can be an indicator as well. The tiles 30x30 cm or larger are normally hard (as, otherwise, considering their size, they would easily break).