[Rockhounds] Physicists Create Lab-Grown Diamond Even Harder Than Natural

[Kreigh Tomaszewski]

Diamond is well-known for being the hardest natural material on Earth,
though synthetic forms
<https://www.sciencealert.com/forget-billions-of-years-scientists-have-grown-diamonds-in-just-150-minutes>
have
been developed that are even tougher – a feat that researchers have managed
again, through a new approach to diamond formation.

The team put graphite (another super-hard material) under an intense amount
of pressure, before heating it to 1,800 K (that's 1,527 °C or 2,780 °F).
The resulting diamond has a hexagonal lattice crystal structure, rather
than the normal cubic structure.

Hexagonal diamond (or lonsdaleite) was first brought to the attention of
scientists more than 50 years ago <https://www.nature.com/articles/214587a0>,
after it was discovered in a meteorite impact site. The new research is the
first solid evidence that this internal structure boosts hardness.

"Natural and synthetic diamonds mostly have a cubic lattice, whereas a rare
hexagonal structure – known as hexagonal diamond (HD) – has been largely
unexplored due to the low purity and minuscule size of most samples
obtained," write <https://www.nature.com/articles/s41563-025-02126-9> the
researchers in their published paper.

https://www.sciencealert.com/physicists-create-lab-grown-diamond-even-harder-than-natural