Tourmaline (Achroite, Dravite, Rubellite, Indicolite, Verdelite, Siberite)
Play Ball (CHECK77.JRG)
By Jeff R. Graham
Copyright 2003
85.8% Light Return
Angles for R.I. = 1.62
57 facets + 8 facets on girdle = 65
4-fold, mirror-image symmetry
96 index
L/W = 1.000 T/W = 0.350 T/L = 0.350
P/W = 0.431 C/W = 0.167
H/W = (P+C)/W+0.02 = 0.618
P/H = 0.698 C/H = 0.270
Vol./W^3 = 0.217
Addition # 8 – Cut this in refractive indexes 1.62 to 2.14 (90.2%) with no changes. This is pretty quick to cut and works well in about any material. I like it in medium colors.
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.
