Mazanec
spending too much on rocks
Member since March 2004
Posts: 355
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Post by Mazanec on Jan 25, 2016 12:08:58 GMT -5
Topaz Emerald Ruby/Sapphire I imagine they would be expensive. I also imagine they would take a long time (am I right?). But could it be done?
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,169
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Post by jamesp on Jan 25, 2016 12:55:20 GMT -5
Topaz Emerald Ruby/Sapphire I imagine they would be expensive. I also imagine they would take a long time (am I right?). But could it be done? Silicon carbide should handle them all, ruby the slowest as it is the hardest. Topaz has a knoop hardness of 1340, Silicon carbide 2500. Could not find knoop for ruby in chart, but a search would tell. Almandine garnet is knoop 1360 and folks tumble them well. Expensive tumble
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Post by pauls on Jan 25, 2016 16:56:54 GMT -5
Ruby and Sapphire are Aluminium Oxide and hard as hell, they need diamond to polish. I have made cabs out of star Saphires, Silicon Carbide sanding discs just don't touch them. There are people on the Sapphire fields here in Australia that tumble them using cheap Chinese Diamond powders, thats the bombs, not good cutters, the good cutters get sold to the Thias who cut them and call them Thai Sapphires. Topaz can be a problem because they have an excellent cleavage and can split down the cleavage in the tumbler, its really a waste of a Topaz if they are any good though as all you end up with is something that looks like a piece of tumbled glass. I know of people who do tumble them to clean them up so they can pick out the cutters for faceting but I wouldn't. Emerald is Beryl and quite fragile, I doubt it would tumble well.
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