The hardest naturally occurring substance on Earth is diamond, a crystalline form of carbon. Diamonds are formed under extreme pressure and heat deep within the Earth’s mantle, resulting in a highly ordered lattice structure that gives them their unparalleled hardness and brilliance. In addition to their use in jewelry, diamonds are valued in various industries for their cutting and grinding capabilities. Their hardness makes them ideal for tools that require precision, like saws and drills. Furthermore, diamonds have significant cultural and economic importance, symbolizing luxury and lasting commitment, especially in engagement rings.