Edited sentence: C60 has also been used to create an even harder material: aggregated diamond nanorods.Characterization of superhard materials produced from fullerenes under high pressure conditions is complicated by very poor crystallinity of samples.Hardness of 3D polymerized materials is a controversial issue: early claims of hardness exceeding that of diamond are not confirmed by independent groups during last 10 years.In fact, hardest samples were reported to be nearly amorphous and most likely with most of fullerene cages collapsed into diamond-like carbon phase.Several independent studies confirmed synthesis of materials with very high hardness (close to hardness of diamond) but none of them were harder than diamond