Chinese Researchers Claim Breakthrough in Creating Elusive Hexagonal Diamond

The new diamond is slightly harder, stiffer, and more resistant to oxidation compared to regular cubic diamonds.

Published on Mar. 5, 2026

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After decades of failed attempts, a team of Chinese researchers claims to have successfully synthesized a millimeter-sized, pure-phase hexagonal diamond, a rare form of the material that is hypothesized to be around 50% harder than regular diamonds. The researchers used a highly specific method of compressing graphite at elevated temperatures to produce the hexagonal diamond, which they confirmed through X-ray analysis and atomic-scale microscopy.

Why it matters

The existence of hexagonal diamonds has been a long-standing controversy in materials science, with numerous claims over the years that have failed to withstand scrutiny. If the Chinese team's findings hold up, it could pave the way for the development of an even harder and more durable form of diamond with potential industrial applications.

The details

The researchers used highly oriented graphite, a synthetic carbon material, and subjected it to extreme pressure (20 gigapascals, or 200,000 times atmospheric pressure) and temperatures between 1,300 and 1,900 degrees Celsius. They found that applying the pressure from the top, rather than the sides, was key to producing the pure hexagonal diamond structure. While the hexagonal diamond was slightly harder and stiffer than regular diamonds, it was not as much as the hypothesized 50% difference.

  • The existence of hexagonal diamonds was first hypothesized in 1962.
  • In 1967, geologists claimed to have found naturally occurring hexagonal diamonds in a meteorite, naming the structure 'lonsdaleite'.
  • In the early 2020s, other attempts to create hexagonal diamonds produced only tiny or short-lived versions.
  • The latest study by the Chinese researchers was published in March 2026.

The players

Chongxin Shan

The co-lead author of the study and a physicist at Zhengzhou University in China.

Oliver Tschauner

A crystallographer at the University of Nevada, Las Vegas, who peer-reviewed the study and called it the 'first very accurate characterization of this elusive material'.

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What they’re saying

“That 'should be enough to convince hexagonal-diamond skeptics that the material exists and can be made in the lab.”

— Chongxin Shan, Co-lead author (Nature News)

What’s next

The researchers claim their work 'resolves the long-standing controversy on the existence of hexagonal crystals,' but the findings will need to be further validated and scrutinized by the broader materials science community.

The takeaway

The successful synthesis of a pure-phase hexagonal diamond, if confirmed, could lead to the development of an even harder and more durable form of diamond with potential industrial applications, resolving a decades-long scientific controversy.