Historically observed hexagonal diamond (lonsdaleite) in meteorites and labs has faced verification questions due to diffraction pattern ambiguities, with prior claims disputed because defective cubic diamond can mimic hexagonal signals.

New work aims to settle the controversy by precise synthesis and rigorous characterization, reinforcing the case for bulk hexagonal diamond.

If validated broadly, hexagonal diamonds could offer industrial advantages thanks to potentially superior hardness and stability, impacting cutting tools and thermal management materials.

Tests indicate hexagonal diamond samples are stiffer, more oxidation-resistant, and slightly harder than cubic diamond, suggesting potential use in quantum sensing and other high-performance applications.

X-ray and atomic-scale microscopy confirm a hexagonal carbon lattice with few defects, providing strong evidence for bulk hexagonal diamonds.

Two other independent 2025 studies report similar lab-made results, reinforcing reproducibility and practicality of hexagonal diamond, though earlier X-ray signals were less clear.

Peer review and expert commentary frame the new work as the most convincing characterization to date of hexagonal diamond.

Hexagonal diamond was produced by compressing highly oriented graphite at around 20 gigapascals and temperatures between 1,300 and 1,900 degrees Celsius, using a specific pressing angle to apply axial pressure.

The study yielded millimeter-sized hexagonal diamond samples from highly oriented graphite under extreme pressure and temperature conditions.

Researchers in China report the synthesis and characterization of hexagonal diamond, describing phase-pure, millimeter-scale samples with potential hardness and oxidation resistance advantages.

The Nature paper claims the hexagonal diamond is potentially harder and more oxidation-resistant than cubic diamonds, highlighting its practical promise.

X-ray diffraction is crucial to distinguish hexagonal structure from defective cubic diamond, with researchers reporting distinctive peaks supporting hexagonal topology.