Faceting Design Diagram: 77 Turbo – Tourmaline – Achroite, Dravite, Rubellite, Indicolite, Verdelite, Siberite


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

77 Turbo (MIR34.JRG)
By Jeff R. Graham
Copyright 2004
93.9% Light Return
Angles for R.I. = 1.62
71 facets + 7 facets on girdle = 78
7-fold, mirror-image symmetry
77 index
L/W = 1.026 T/W = 0.389 T/L = 0.379
P/W = 0.417 C/W = 0.162
H/W = (P+C)/W+0.02 = 0.599
P/H = 0.697 C/H = 0.270
Vol./W^3 = 0.195

Addition # 9 – Cut in refractive indexes 1.62 to 2.14 with no changes. This is bright with a lot of sparkle. It looks like it has thousands of facets. Light to medium saturated stones works well although it is quite nice in a quality Garnet.


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.