1. Diamond, a particular form, or allotrope, of carbon, is the hardest material we know of. It’s more than twice as hard as the closest competition, silicon nitride and cubic boron nitride.
2. That extraordinary hardness arises from a strong and inflexible structure: Five atoms form a tetrahedron and share electron pairs with each other.
3. In nature, diamond is typically created under extremes of pressure and temperature, deep in Earth’s mantle — about 90 miles or more beneath our planet’s surface.
