Tourmaline (Achroite, Dravite, Rubellite, Indicolite, Verdelite, Siberite)
Shutter (DOME26.JRG)
By Jeff Graham
Copyright 2007
82.4 % Light Return
Angles for R.I. = 1.62
65 facets + 8 facets on girdle = 73
8-fold symmetry
96 index
L/W = 1.000 T/W = 0.211 T/L = 0.211 P/W = 0.415 C/W = 0.315
H/W = (P+C)/W+0.02 = 0.750 P/H = 0.553 C/H = 0.420
Vol./W^3 = 0.259
Addition # 13 – Cut in refractive indexes 1.62 to 2.14 with no changes. This is designed for light saturated rough, and is best cut in a large stone. The light flash is very interesting and this is pretty unique.
Detailed faceting instructions by Jeff Graham available at The Rock Peddler
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.
