Researchers in China recently reported creating what they believe to be the first pure samples of hexagonal diamond. This rare diamond variant is theorized to be super strong and has been found in meteorites, particularly those from fragmented dwarf planets.
Diamonds, known for their hardness, are typically cubic in structure. The carbon atoms in natural diamonds are arranged neatly in a cube, making them the hardest material on Earth, as measured by the Mohs hardness scale. But hexagonal diamond, which organizes carbon atoms in a hexagonal lattice, might be even tougher. Imagine a honeycomb structure — that’s how these atoms line up.
The idea of hexagonal diamond isn’t new. Back in 1962, scientists at the Pittsburgh Coal Research Center suggested that carbon could arrange itself differently. In 1967, hexagonal diamond was first observed in a lab, but doubts lingered about its true properties and whether it could indeed be harder than cubic diamond.
The search for hexagonal diamond led researchers to meteorites known as ureilites, which contain high amounts of diamond. The first natural occurrences were confirmed in the Canyon Diablo meteorites in Arizona. Yet, skeptics argued that what was termed “hexagonal diamond” might just be flawed cubic diamond.
Despite the debates, recent studies, including one from 2025, have successfully identified hexagonal diamond in various samples. The challenge has always been the difficulty in isolating pure samples, as hexagonal diamond is often mixed with other forms like cubic diamond or graphite.
In a new research published in March in Nature, scientists managed to synthesize pure hexagonal diamond samples about 1.5 millimeters in diameter. They found that hexagonal diamond is not only harder than its cubic counterpart but also more resistant to oxidation. This means it can withstand higher temperatures without reacting with oxygen, which has significant implications for fields like drilling.
As physicist Chong-Xin Shan from Zhengzhou University noted, hexagonal diamond could transform tools used for cutting and polishing and could even play a role in thermal management and quantum sensing technologies. The potential applications of this material are vast and could impact several industries.
In crafting these samples, researchers compressed highly ordered graphite under extreme conditions: high pressure and temperatures over 2,300 degrees Fahrenheit. They observed that at high temperatures, hexagonal diamond tends to revert to cubic diamond, making the process delicate.
This discovery opens new doors. Aside from potential industrial applications, understanding hexagonal diamond’s presence in meteorites may help scientists unravel the history and formation of our solar system.
If you’re looking for more information about hexagonal diamond, you can check out the detailed study published in Nature here.
