Ultrahard fullerite
Ultrahard fullerite (C60) is a unique version of buckminsterfullerene with three-dimensional polymer bonds. This should not be confused with P-SWNT fullerite, even though that material is also a polymerized version of fullerene. It has been shown 1 (http://www.mrs.org/publications/jmr/jmra/articles/1997/nov/p03109.pdf) 2 (http://www.mtu-net.ru/nanoscan/files/article_03.pdf) that ultrahard fullerite when testing diamond hardness with a scanning force microscope can scatch diamond. In turn, using more accurate measurments, these values are now known for diamond hardness. A Type IIa diamond (111) has a hardness value of 167±6 GPa when scratched with an ultrahard fullerite tip. A Type IIa diamond (111) has a hardness value of 231±5 GPa when scratched with a diamond tip which leads to hypothetically inflated values. Ultrahard fullerite has a hardness value of 310 GPa, though the actual value may range ±40 GPa, since testing done using an ultrahard fullerite tip on ultrahard fullerite will lead to, like diamond on diamond, distorted values. It is thought that beta carbon nitride will have a hardness value, if harder than diamond, less than that of ultrahard fullerite.