Diamonds remain the most scratch-resistant material known to humanity. Metals like titanium are far less scratch-resistant, and even extremely hard ceramics or tungsten carbide cannot compete with diamonds in terms of hardness or scratch-resistance.

Is there an unbreakable material?

Graphene, even in an imperfect form, remains the strongest material in the world, according to new research from Columbia University, which found that the single layer of latticed carbon atoms is virtually unbreakable even when stitched together like a quilt.

What is the toughest material?

Diamond is the hardest known material to date, with a Vickers hardness in the range of 70–150 GPa. Diamond demonstrates both high thermal conductivity and electrically insulating properties, and much attention has been put into finding practical applications of this material.