![\"A](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2026\/03\/d41586-026-00711-9_52139416.jpg\"\/)
<\/p>\n <\/p>\n
Conventional diamond, called cubic diamond, is known as the hardest substance in the world. But researchers think hexagonal diamond could be harder.Credit: Mats Silvan\/Getty<\/p>\n
Diamond<\/a> is famously known as the hardest mineral on Earth. But researchers have been pursuing an unusual variant of it \u2014 known as hexagonal diamond \u2014 that might be even harder. After decades of claims and counterclaims about whether this mysterious material can be synthesized in a laboratory, researchers in China report that they have done it1<\/a>.<\/p>\n Scientists covet the material because it \u201chas potential applications in many fields, for example in cutting tools, in thermal management materials and in quantum sensing<\/a>\u201d, says Chongxin Shan, a physicist at Zhengzhou University, who co-led the work.<\/p>\n \u201cThere are hundreds of claims from people who believe they have seen it,\u201d says Oliver Tschauner, a mineralogical crystallographer at the University of Nevada, Las Vegas, who peer-reviewed the paper. \u201cBut this is the first very accurate characterization of this elusive material.\u201d<\/p>\n Shock value<\/p>\n Conventional diamond consists entirely of carbon atoms arranged into tetrahedra, which ultimately form a cubic crystal structure. Viewed from a specific angle, this lattice of atoms looks like a stacked series of buckled honeycomb layers. Each successive layer is offset slightly relative to its neighbours, in a pattern that repeats every three layers. But in 1962, researchers predicted that diamond could adopt a different structure \u2014 one with hexagonal features \u2014 in which the pattern repeats every two layers2<\/a> (see \u2018Diamond\u2019s elusive form\u2019).<\/p>\n In conventional, or cubic, diamond, the carbon bonds between layers are marginally weaker than those within layers, which limits diamond\u2019s strength. In the hexagonal form, the bonds between layers are shorter and stronger than those in cubic diamond, and predictions suggest that these features should make hexagonal diamond more than 50% harder.<\/p>\n In 1967, researchers reported finding hexagonal diamond in a meteorite found in Arizona, which was part of the space rock that created the iconic Meteor Crater nearby3<\/a>. The team suggested that the shock of the impact had transformed graphite in the meteorite into hexagonal diamond, and named this new mineral lonsdaleite, after pioneering crystallographer Kathleen Lonsdale.<\/p>\n Around the same time, a separate research team said that it had produced hexagonal diamond in the lab by heating and compressing graphite4<\/a>. But some scientists have cast doubt on that report5<\/a>. And others argued that lonsdaleite wasn\u2019t hexagonal diamond at all; they said it was just cubic diamond with several defects6<\/a>. <\/p>\n Peak demand<\/p>\n Much of the debate stems from the X-ray diffraction experiments used to discern the material\u2019s crystal structure, Tschauner explains. In this type of experiment, as X-rays scatter through a crystal, some of them combine and produce peaks in X-ray intensity that reveal atoms\u2019 positions. However, the pattern of diffraction peaks obtained from highly defective cubic diamond would closely mimic those of hexagonal diamond, Tschauner says. To demonstrate the hexagonal structure conclusively, a few extra telltale peaks must be present. \u201cThis new paper shows those peaks,\u201d he says. \u201cThat\u2019s why I believe it.\u201d<\/p>\n![\"DIAMOND\u2019S](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2026\/03\/d41586-026-00711-9_52143812.png\"\/)
<\/p>\n
![\"\"](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2026\/03\/d41586-026-00711-9_50729074.jpg\"\/)
<\/p>\n