Hardness is not a true property of materials, since it depends on certain properties of a material, such as ductility, resistance, rigidity, elasticity, viscosity, deformation, among others. Rather, it is a property that is attributed to any object capable of resisting change when it is suffers abrasion or scratching. Hardness is seen as a “attribute” of objects that is difficult to physically alter when subjected to different forms of deformation.

To measure the hardness of something you need a scale and instruments that allow it. The first scale was devised by German geologist Friedrich Mohs. Mohs worked on cataloguing and developing a scale to evaluate the hardness of various minerals. He selected ten minerals of distinctly different hardness that ranged from a very soft mineral (talc) to a very hard mineral (diamond). In this way, he was able to determine that diamond is the hardest material.