Forums Techniques, Tricks, and Tips Cutting Dark Stones

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      ScottWilliam
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      @ScottWilliam

      I’m in the process of cutting an umbalite garnet that will end up around 4.5 carats!! I was about to polish the pavilion when I had second thoughts about the way I manipulated the design angles in GemCad. The design is call “Lassitude” by Arya Akhavan.

      http://www.gemologyproject.com/wiki/index.php?title=Akhavan_-_Lassitude

      In gem cad I fixed the angles to be more appropriate for a garnet. Since the garnet was dark I also added limiting factors to make sure that the angles only decreased, allowing for a lighter colored stone. My current diagram has the p5 facet at 39.5 and c5 facet at 29.65. Should I lower the angles even further to get close to the critical angle of garnet?

      Here is a link to an example of the last 1.59 umbalite I cut of identical color. It’s dark when viewed indoors but brightens well enough outside. Considering my next stone is much larger, I am very concerned about color. Can anybody offer some reassurance to make sure I am not ruining what should be a wonderful stone?

      https://www.etsy.com/listing/398923587/natural-unheated-loose-159-carat?ref=shop_home_active_2

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