Diamonds are not the hardest natural substance

While diamonds are considered the hardest natural substance ranking 10 on the Mohs scale (maximum value), this perception requires refinement. Scientists theorized and experimentally demonstrated certain synthetic carbon structures, particularly aggregated diamond nanorods (ADNRs), possess theoretical hardness exceeding diamond. These nanorods consist of diamond crystals bonded in specific orientations creating material potentially 5-10% harder than conventional diamonds. However, these materials currently exist only in laboratory conditions in tiny quantities, making them impractical for applications. Regarding natural substances, diamond remains the hardest known material. The concept of 'hardness' is complex: different measurements emphasize different properties. Mohs hardness measures scratching resistance; other measures like indentation hardness may show different results. Additionally, diamond, despite hardness, is brittle—it fractures under certain impacts. Materials like cubic boron nitride approach diamond hardness potentially surpassing it in specific applications.