Lab-Forge Confirms Hexagonal Diamond, Ending a Half-Century Controversy

Chinese researchers report the synthesis of a millimeter-sized, phase-pure hexagonal diamond by compressing graphite at 20 GPa and temperatures up to 1,900°C, with X-ray and atomic-scale imaging confirming a hexagonal crystal structure; the diamond is slightly harder and more oxidation-resistant than cubic diamonds, suggesting the long-sought material exists and could have practical uses, though the hardness gain is not the often-cited 50%.