ADNRs are also 0.3% denser than regular diamond. The ADNR material is also harder than type IIa diamond and ultrahard fullerite.
A process to produce the substance was discovered by physicists in Germany, led by Natalia Dubrovinskaia, at the University of Bayreuth in 2005. ADNRs are made by compressing allotropic carbon fullerene molecules (generally 60 carbon atoms per molecule) to a pressure of 20 GPa, while at the same time heating to 2500 kelvin, using a unique 5000-metric-ton (50 MN) multi-anvil press. The resulting substance is a series of interconnected diamond nanorods, with diameters of between 5 and 20 nanometres and lengths of around 1 micrometre each.