docharber
has rocks in the head
Member since October 2008
Posts: 716
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Post by docharber on Jul 5, 2011 22:30:40 GMT -5
i recently bought a few pieces of idaho star garnet rough in an estate sale. Since garnets crystallize in tyhe cubic system with three way symmetry, how do you orient the stones to bring out the star? The crystals re split / broken. i can't attest to their quality but they appear rather to oppaque and gray to make pretty stones, but I want to practice on them. I can only imagine the stonesinclusions must form radially and symmetrically in whick case they should astar in any direction. I hate to grind them up trying to find out, though. Any advice?
Mark H.
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Post by FrogAndBearCreations on Jul 5, 2011 23:07:23 GMT -5
you could tumble polish them first to see just where the star is in order to then cab it.
I would start at prepolish then polish as you don't want to take much stone off.
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Post by bobby1 on Jul 5, 2011 23:40:43 GMT -5
If you have a broken segment of a crystal use the largest flat face of the original crystal as the back of the cab. Dome the point that is opposite this flat face because it is closest to the center of the original unbroken crystal. This material has the star on the inside center of the original crystal. If you start grinding from the outside you won't see any star. Here is some info from this gem guide:    I'm not sure if this guide is still in print or available but it is very helpful for star stone cutting. Bob |
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Post by Tony W on Jul 6, 2011 10:07:05 GMT -5
I'm working some now. Tumbling helps, and a bit of mineral oil and sunlight help to spot the asteration oft times. I'm working the ones that are readily visible after some tumbling, and some have nice stars, but I also just hit the wheels all around, if I don't want to tumble, with the rougher pieces to try to get a bit of clearity so the silk will show, if it is going to. T
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docharber
has rocks in the head
Member since October 2008
Posts: 716
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Post by docharber on Jul 7, 2011 23:59:04 GMT -5
thanks for the input guys. I have star almandine material and by the diagram the silk lies parallel to the crystal faces all around so it shouldn't be too hard to get it right if there's a decent star to be seen in it. There's definitely a lot of silk- probably too much. i have used litytle African almandine garnets as filler in tumbling and I'm impressed the are so durable. I'll toss a couple of tghese in my next grind and then apply mineral oil as suggested. I screwed up a piece of expensive star rose quartz already and I'm a bit nervous about playing with a potentially nice gem. i'm going to look for that publication online.
Mark H.
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docharber
has rocks in the head
Member since October 2008
Posts: 716
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Post by docharber on Jul 8, 2011 15:27:45 GMT -5
I will put a couple pieces in my next tumbler load. I see from the pages ipictured that the silk runs parallel to the crystal faces, and oddly enough an almandine garnet is illustrated. Gotta get one of those books. Anyway, I'll try the mineral oil in sunlight trick and tumbling first, and maybe just grinding away to see if I can get it right. i've already messed up a piece of roe quuartz star rough and don't want to repeat that experience- this looks simpler. Rhanks guys!
Mark H.
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Post by 1dave on May 7, 2019 11:00:12 GMT -5
A drop of glycerine on the surface will show what rays are available in that spot.
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