Tourmaline (Achroite, Dravite, Rubellite, Indicolite, Verdelite, Siberite)
Royal Mine (CHECK63.JRG)
By Jeff R. Graham
Copyright 2003
87.4% Light Return
Angles for R.I. = 1.62
61 facets + 8 facets on girdle = 69
4-fold, mirror-image symmetry
96 index
L/W = 1.000 T/W = 0.372
T/L = 0.372 P/W = 0.441 C/W = 0.182
H/W = (P+C)/W+0.02 = 0.643
P/H = 0.686 C/H = 0.282
Vol./W^3 = 0.234
Addition # 8 – This one is really neat. I have always liked an antique/mine cut and this one with a diamond top is cool. Cut in refractive indexes 1.62 to 2.14 (89.7%) with no changes. This works in about any material.
Random – Cosine – ISO
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.
