The brilliantly shiny diamond is more than just pretty; it’s one of the hardest minerals on Earth, with a name derived from the Greek word adámas, meaning unbreakable. Scientists have now engineered a harder form of diamond known as bulk hexagonal diamond (HD)—a crystalline structure that has been theorized for over half a century to have physical properties superior to those of conventional diamond.

In a study published in Nature, researchers from China synthesized bulk hexagonal diamond, ranging from 100-µm-sized to mm-sized, with a highly ordered structure by compressing and heating high-quality graphite single crystals under pressure conditions as uniform as possible.

The designed material, which was recoverable under ambient conditions, unveiled the previously elusive structural world of HD, opening new avenues for exploring its potential as a technologically superior material.