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:::A simple search on Google shows there is an 'absolute hardness' scale; in fact, there appear to be at least two: the Rosiwal absolute hardness scale; and the Knoop absolute hardness scale. Also, how can a non-existent scale yield real numbers like the ones in this article (although I've more commonly seen 140000 for Diamond, not the 1500 given above; I suppose this might be the Rosiwal vs. Knoop scales.) -- SJK |