Most faceting diagrams are written for Quartz which has an angle of 43 for the mains. Cutting in other materials means you need to translate the angles of all the facets based on the "best" angle for the chosen material. To make this easier we have included here a spreadsheet that you can download and utilize to do the calculations for you. Enter the Angle of the material you want to use under the heading "Desired", the value in the spreadsheet you are replacing is "37". The rows below are an example only. You can change the Pavilion and Crown angles for your pattern in column B and the new angles will appear in column E. 

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