To misquote a famous song, “Diamonds are industry’s best friend.” Cubic diamond is the hardest mineral on Earth and is used in everything from precision cutting tools to high-performance semiconductors as well as expensive jewelry. But there is a rare and potentially tougher form called hexagonal diamond (HD), which has long been the subject of theories and debate over its actual existence. But now researchers from China claim to have created this elusive form of carbon in the lab.

Hexagonal diamond (also known as lonsdaleite) is usually found at sites of meteorite impacts. But because the quantities are so small and mixed with minerals, some scientists doubted it was a distinct material. In a paper published in the journal Nature, researchers describe how they made a bulk piece of pure HD using extreme pressure and heat.