Tourmaline (Achroite, Dravite, Rubellite, Indicolite, Verdelite, Siberite)
Bethlaham Star (MC76.JRG)
By Jeff R. Graham
Copyright 2001
82.2% Light Return
Angles for R.I. = 1.62
45 facets + 6 facets on girdle = 51
2-fold, mirror-image symmetry
96 index
L/W = 1.335 T/W = 0.238 T/L = 0.179
P/W = 0.406 C/W = 0.274
H/W = (P+C)/W+0.02 = 0.700
P/H = 0.580 C/H = 0.391
Vol./W^3 = 0.269
Addition # 7 – This is really very nice. When cutting the crown cut C1,C3,C4,C5,C6 as evenly as you can, there are no meets. You may have to cut the crown a couple of times to get the tiers even.
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.
