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Revision as of 15:59, 19 January 2007 by Tom Goodwin, G.G. (talk | contribs) (Acknowledgement of comment regarding Moh's scale vs. Rosiwal scale)
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While spinel and topaz are both 8 on Moh's scale, there is a large difference between 8 and 9 on the scale as reflected by the Rosiwal scale of hardness. With this scale corundum is 1,000 times harder than the benchmark topaz on Moh's scale.Tom Goodwin, G.G. 14:29, 19 January 2007 (PST) Therefore, descriptions of "slightly softer" or "slightly harder," really need to be quantified, and can be. Tom Goodwin, G.G. 14:29, 19 January 2007 (PST)

There are many hardness scales (vickers, rockwell, brinell, knoop, wilks, brookes etc). The proper place to add information is first to describe them in the hardness page and then refer to that. --Doos 14:40, 19 January 2007 (PST)
When I get the chance I'll write about the differences in hardness scaling. Tom Goodwin, G.G. 14:59, 19 January 2007 (PST)