Why is diamond the hardest natural material on Earth?

Diamond ranks 10 on the Mohs hardness scale, making it the hardest known material, whether grown in a lab or formed underground. That hardness comes from carbon atoms arranged in a tetrahedral lattice, where each atom bonds to four others with exceptional strength. Lab-grown diamonds replicate this exact crystal structure using high-pressure, high-temperature (HPHT) or chemical vapour deposition (CVD) processes, reaching the same atomic geometry as any mined stone. The result is chemically, optically, and physically identical, confirmed by IGI certification. For buyers, this means durability is not a variable between lab-grown and mined diamonds. A lab-grown diamond set in a Valquère ring will resist scratching from every other material except another diamond. If you are comparing stones for everyday wear, hardness is one spec where the origin of the diamond makes no practical difference.