Faceting Design Diagram: Step’in “C” – Tourmaline, Achroite, Dravite, Rubellite, Indicolite, Verdelite, Siberite


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

Jeff Graham Facet Designq

 Jeff Graham Facet Design

 

 

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.

 

Jeff Graham Facet Design

Detailed faceting instructions by Jeff Graham available at The Rock Peddler

Gram Faceting Archive of Information
This edited version of an article by the late Jeff Graham is part of a special archived informational series from Gram Faceting. Used with permission.