herb
spending too much on rocks
Member since November 2011
Posts: 476
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Post by herb on Oct 31, 2019 14:47:07 GMT -5
Hi everyone! I have a few small pieces of sugilite rough that I wanted to slab for cabs. Unfortunately, I dont know much about it. Does it need to be orientated in a particular direction? I'm thinking not. I've heard it is difficult to get a good polish on, any hints or experiences to share? Thanks, Herb
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nik
spending too much on rocks
Member since May 2019
Posts: 315
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Post by nik on Nov 1, 2019 7:29:40 GMT -5
I've only cut a couple small stones. From what I recall, orientation was not important, and it polished well with tin oxide. I have not cut any of it since switching to diamond abrasives, so your milage may vary depending on your set up
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herb
spending too much on rocks
Member since November 2011
Posts: 476
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Post by herb on Nov 3, 2019 9:42:47 GMT -5
As a follow up question, I've heard that soaking sugilite in Iron Out helps bring out the purple color. Anyone try it? I'm guessing you'd have to soak a finished or at least partly finished cab since the effects of the Iron Out probably wouldn't reach too far into a slab?
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Post by opalpyrexia on Nov 3, 2019 10:09:09 GMT -5
My single sugilite experience was trimming and recutting two tongue cabs to redesign a customer's pendant. I had no issues cutting with my Pixie and the sugilite polished up great on my 14,000 wheel. Although orientation was defined by the pendant, the pieces I cut did not show any variation with orientation when I was inspecting my work.
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Deleted
Deleted Member
Member since January 1970
Posts: 0
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Post by Deleted on Nov 3, 2019 13:20:37 GMT -5
I've never tried Iron-Out with sugilite, but based on it forming in an acidic environment and that it contains metal oxides, I'd be careful. If you have a small scrap, you might want to test it first. The GIA Guidelines for Gemstone Durability in Jewelry also recommends avoiding putting sugilite into acidic pickling solutions, so that would also argue for caution.
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gemfeller
Cave Dweller
Member since June 2011
Posts: 4,064
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Post by gemfeller on Nov 3, 2019 13:45:38 GMT -5
Sugilite color varies a lot, from very dark purple to varying shades of magenta to lovely lilac-to-pink hues in the gel (translucent) type. The only issue in orientation I've found would be to separate gel and opaque types, which can occur in the same rough. That might also be true in pieces that mix blue richterite or pinkish-red bustamite with sugilite. These are often encountered and IMO should be cut to display the best colors. I've cut a fair amount of sugilite and the best polish (for me) has been Holy Cow! oxide on a synthetic polishing pad. It's good to know that opalpyrexia has had good results with diamond. As for Iron Out, I've never previously heard of that technique. I'll give it a try on some of my scrap pieces.
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Post by rmf on Nov 3, 2019 22:02:59 GMT -5
Iron-Out has a main ingredient of sodium dithionite (chemical formula is Na2S2O4). If that looks familiar to you it is because Sulfuric Acid is H2SO4. So I would guess it is more mild but still acidic. Especially since you put it in a water solution you will have the same ions working as Sulfuric acid in water. the chemical formula for sugilite is KNa2(Fe, Mn, Al)2 Li3 Si12 O30. so it is a silicate and should be inert. However, who knows what is with the sugilite and it may be soluble so as previously suggested use a scrap.
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