Faceting Design Diagram: Cross Mod-Square – Tourmaline – Achroite, Dravite, Rubellite, Indicolite, Verdelite, Siberite


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

Cross Mod-Square (TLINE7.JRG)
By Jeff R. Graham
Copyright 1993
83.8% Light Return
Angles for R.I. = 1.62
77 facets + 12 facets on girdle = 89
4-fold, mirror-image symmetry
96 index
L/W = 1.000 T/W = 0.527 T/L = 0.527
P/W = 0.486 C/W = 0.202
H/W = (P+C)/W+0.02 = 0.709
P/H = 0.686 C/H = 0.286
Vol./W^3 = 0.304

Addition # 1 – This design has very deep breaks. In order not to waste material cut a preform, see heading for measurements. The depth of this design helps light material and gives the stone a nice shape, 1-18cts. Cut in refractive indexes 1.62 to 1.93 (86.8%) with no changes. Works well in Topaz also…


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.