Which is the hardest natural material?

Diamond is the hardest naturally occurring material known, earning the top score of 10 on the Mohs scale of mineral hardness. It forms deep in the Earth’s mantle, where carbon atoms are subjected to enormous pressure and heat, bonding into an extremely rigid crystal lattice. This structure makes diamond exceptional at resisting scratches, which is why it is used in cutting, grinding, and drilling tools as well as jewelry. Scientists have created even harder synthetic materials in the lab, and certain rare natural substances like lonsdaleite (a diamond variant formed in meteorite impacts) may be harder still, but ordinary diamond remains the benchmark for natural hardness.