Faceting Design Diagram: Scribe Triangle – Tourmaline – Achroite, Dravite, Rubellite, Indicolite, Verdelite, Siberite


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

Scribe Triangle (TLINE4.JRG)
By Jeff R. Graham Copyright 1993
79.1% Light Return
Angles for R.I. = 1.62
49 facets + 9 facets on girdle = 58
3-fold, mirror-image symmetry
96 index
L/W = 1.020 T/W = 0.360 T/L = 0.353
P/W = 0.424 C/W = 0.182
H/W = (P+C)/W+0.02 = 0.625
P/H = 0.677 C/H = 0.291
Vol./W^3 = 0.207

Gram Book 1 – Cut this design in medium to light material. A larger size stone works best because of the narrow crown facets. It cuts easy and fast for a triangle, and has nice sparkle, 1-12cts. Cut in refractive index 1.62 to 1.76 (79.4%) with no changes.

 

 


Random – Cosine – ISO

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.