What is the hardest natural substance on Earth?

Diamond is recognized as the hardest natural substance on Earth due to its unique crystal structure. In a diamond, carbon atoms are arranged in a very specific way, forming a tetrahedral lattice that is incredibly strong. This structure enables diamonds to withstand a significant amount of pressure and scratch from other materials, making them the hardest known natural material.

The other substances listed, while they are indeed hard and valuable, do not compare to the hardness of diamonds. Gold is a metal that is malleable and can be easily shaped, meaning it is not very hard at all. Quartz, though a hard mineral, is not as hard as diamond on the Mohs scale of hardness. Ruby, a variety of corundum, is also very durable but still ranks below diamond in terms of hardness. Each of these materials has its own unique properties and uses, but diamond leads the ranking when it comes to hardness.