Tourmaline (Achroite, Dravite, Rubellite, Indicolite, Verdelite, Siberite)

Step'in "C" (MIR77.JRG)
By Jeff R. Graham
Copyright 2005
88.8% Light Return
Angles for R.I. = 1.62
29 facets + 8 facets on girdle = 37
2-fold, mirror-image symmetry
96 index
L/W = 1.000 T/W = 0.257 T/L = 0.257 P/W = 0.438
C/W = 0.229 H/W = (P+C)/W+0.02 = 0.687 P/H = 0.637 C/H = 0.334 Vol./W^3 = 0.320

Addition # 10 - Cut in refractive indexes 1.62 to 1.76 with no changes. This is designed for dark axis "c" Tourmaline. It is easy to cut and works well. It has step/checker reflection. The crown can be lowered to 30 degrees for very dark material.

 

 

 

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