The team put graphite (another super-hard material) under an intense amount of pressure, before heating it to 1,800 K (that's 1,527 °C or 2,780 °F). The resulting diamond has a hexagonal lattice crystal structure, rather than the normal cubic structure.

The newly produced diamond has a hardness of 155 gigapascals (GPa), which is essentially a pressure measurement: the pressure the material can withstand. Natural diamond, by comparison, tops out at around 110 GPa in hardness.