An ultra-hard carbon crystal created artificially by subjecting solvated carbon-60 molecules to extremely high pressures more than 300,000 times than that of atmosphere. The resulting carbon, known as OACC, is 58% harder than diamond with a unique atomic structure that consists in both crystalline and disordered elements.

Most carbons such as graphite, diamond, nanotubes, graphene and charcoal are either classified as crystalline with repeating atomic units or amorphous having no long-range structural order. As a crystalline material composed of amorphous clusters, OACC is the first hybridised carbon structure ever seen, being partly amorphous and partly crystalline.