Top 5 of Anything.com research 2012.
Data is naturally occurring minerals according to absolute hardness. Absolute hardness is measured by a sclerometer.
Please note: Top 5 of Anything.com has not included lonsdaleite or Wurtzite boron nitride on this list because they have to be synthesized in a laboratory by compressing and heating in order to attain a higher hardness than diamond. However if they were to be included on this list Wurtzite boron nitride would have a Mohs of 11.0 and an absolute hardness of 1888 (ranking 2nd). Ionsdaleite would have a Mohs of 12 and an absolute hardness of 2528 (ranking 1st).