On the subject of using semi-precious stones for hones, here's one made of crushed Ruby, no grit comparison is given here though Ruby Polishing Stone Lathe Graver Sharpening Tool on eBay (end time 14-Aug-09 12:11:27 BST)
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On the subject of using semi-precious stones for hones, here's one made of crushed Ruby, no grit comparison is given here though Ruby Polishing Stone Lathe Graver Sharpening Tool on eBay (end time 14-Aug-09 12:11:27 BST)
Well ruby is just corundum which is aluminum oxide so whether its ruby or sappire or common alumina the effect is the same. Most commercial "ruby" is really common alumina opaque and tinged pink so technically its ruby but practically its not. They also can do synthetic xtls too.