Forums Beginner Questions Changing diagram angles

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  • #5026

    brellan217
    Participant
    @brellan217

    I want to make my pieces more vibrant and beautiful. I know there is a way to mathematically change facet angles based on R.I. However, I am at a complete loss as to how to do this.

    Say, for example, I have a diagram for quartz with a RI of around 1.5. My C1 angles are 49.6. I want to cut a beryl with a RI of around 1.6. How do I change that 49.6 specific to quartz to something more appropriate for the RI of the beryl to maximize light refraction?

    I would like to be able to create an Excel file to easily change my refractive indices for me. Is there a formula that works every time?

    Thanks all!

    #5027

    scottwkelley
    Participant
    @scottwkelley

    Try this http://www.rockhounds.com/rockshop/gem_designs/tangent_ratio_form.shtml

    #5028

    Alan Balmer
    Keymaster
    @alanbalmer

    There’s an even easier way, if you have GemCad. You can change the angle on one facet, and the program will tangent ratio the entire half (crown or pavilion) of the design. The companion GemRay program will help you find the angles which perform best. The newer Gem Cut Studio program will do it all, but I haven’t yet spent much time with it.

    #5029

    brellan217
    Participant
    @brellan217

    Thank you for the replies. I am going to look into the gem cut software. I couldn’t use the gem ray or gem cad software because it was confusing to me. Hoping it helps!

    I tried a Portuguese cut that I transposed once before. The stone came out dead and lifeless. Like a window you could see right through :(. I’m hoping not to repeat that so these answers may help.

    #5033

    You might find that changing the angles from Quartz to Beryl are so close that it really doesn’t make much difference to do it. The previous post that said: Try this http://www.rockhounds.com/rockshop/gem_designs/tangent_ratio_form.shtml will give you a way to make changes to as design to use with an increase of the RI to a “brighter” stone. Don’t try to push this too far up the RI chain as high RI materials may not need to be pushed to the last degree to give you a great stone. Learning to use the design software programs that are available is desirable to verify that changes really will be workable. Don’t try to push high RI designs down to low RI minerals as most won’t work well.
    Dennis Anderson.

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