Tourmaline (Achroite, Dravite, Rubellite, Indicolite, Verdelite, Siberite)
8-12 Star (TLINE21.JRG)
By Jeff R. Graham
Copyright 1995
70.3% Light Return
Angles for R.I. = 1.62
77 facets + 8 facets on girdle = 85
4-fold, mirror-image symmetry
96 index
L/W = 1.000 T/W = 0.454 T/L = 0.454
P/W = 0.493 C/W = 0.224
H/W = (P+C)/W+0.02 = 0.737
P/H = 0.669 C/H = 0.304
Vol./W^3 = 0.276
Addition # 1 – The P1,P2(G),P3 facets can be cut in another order if you want. It could be cut P2(G),P3,P1, use whatever works for you, light to medium material 1-12cts. Cut in refractive indexes 1.62 to 1.93 (89.1%) with no changes. Notice that this is a deep design and it will work well in light colored materials.
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.
