Which property describes diamonds in terms of hardness?

Diamonds are recognized as the hardest known natural material, a property primarily attributable to their unique crystal structure. The carbon atoms in a diamond are arranged in a tetrahedral lattice that maximizes the bonds between them, making it incredibly resistant to scratching and wear. This exceptional hardness is not only a defining characteristic of diamonds but also is the reason they are often used in industrial applications for cutting and grinding tools.

The classification of diamonds as the hardest material is supported by the Mohs scale of mineral hardness, where diamonds register a perfect score of 10. This scale allows for the comparison of hardness of various minerals, placing diamonds at the top. The other options do not accurately reflect the unmatched toughness of diamonds.