Researchers have discovered that diamonds behave differently under extreme conditions than previously believed, changing the broader understanding of their melting point.

The findings come from a study published in Nature Physics on 13 August that reports previous measurements of diamond's melting temperature were more than 1,300°F (700°C) too high.

Researchers at Lawrence Livermore National Laboratory in California used high-powered lasers to compress tiny samples of synthetic diamond until melting occurred. Previous experiments had reported much higher melting points than theoretical predictions, leaving a 20-year gap in understanding.

“It's odd to think of diamond, the hardest natural material on Earth, melting — but melt it does when blasted with extremely powerful lasers under the right conditions,” writes Damien Pine for LiveScience.

“Understanding how diamond responds to shock waves from lasers is an important part of developing nuclear fusion, the process that powers stars. Nuclear fusion is also a potential energy source for the future, so researchers have put a lot of effort into developing models that describe and predict how diamond behaves.”

The team also found that at pressures between 660 and 1,060 gigapascals and temperatures near 12,140°F (6,727°C), solid diamond can coexist with liquid carbon rather than converting to another carbon form. As pressure increases, more diamond melts into liquid carbon.

These findings could help improve nuclear fusion research and the scientific understanding of Uranus and Neptune, where extreme conditions are believed to form diamonds deep within these planets.

This report follows a paper by researchers at the University of Hong Kong published in Science Advances, showing that diamond membranes generate measurable electricity when bent.