Cutting from instructions


If I have instructions and they are designed for lets say quartz RI 1,54. And I have to cut sapphire.
How do I know the angles? i know that you cut quartz 2 degrees deeper, but I have red here that sometimes you can use same degrees for lets say 1,54-2,00 RI with that particular instruction.

If the instructions do not tell that you can use same degrees for 1,54-2,00 what shall I do so I do not cut the gem wrong?

Thank you.

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You can use Snell’s Law to compute the critical angle or angle of total reflection if you know the refractive index of your material. See this little treatise: Refraction, Snell's law, and total internal reflection In simpler terms … add 2 degrees to the crown and pavilion angles for diamonds (40.8 degrees optimum pavilion angle for diamond + 2 = 42.8 [43 will work too] and 35 degrees optimum crown angle for diamond + 2 = 37). Enjoy. :smiley:

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