Faceting Design Diagram: Opposed Step 3.0 – Tourmaline – Achroite, Dravite, Rubellite, Indicolite, Verdelite, Siberite


Tourmaline (Achroite, Dravite, Rubellite, Indicolite, Verdelite, Siberite)

Opposed Step 3.0 (MC9.JRG)
By Jeff R. Graham
Copyright 1999
91.2% Light Return
Angles for R.I. = 1.62
17 facets + 4 facets on girdle = 21
2-fold, mirror-image symmetry
96 index
L/W = 3.000 T/W = 0.873 T/L = 0.291
P/W = 0.501 C/W = 0.360
H/W = (P+C)/W+0.02 = 0.880
P/H = 0.569 C/H = 0.409
Vol./W^3 = 1.579

Addition # 4 – This L/W is not critical and may be changed without causing any problems. The crown can be raised if you have the rough or if you do not want to cut at 6 degrees. I use 6 degrees and it is not hard to cut, but CARE must be taken. This has great flash along the length. Cut this in R.I. 1.62 to 2.14 (87.9%) without changes. 


Random – Cosine – ISO

Detailed faceting instructions by Jeff Graham available at The Rock Peddler

Gram Faceting Archive of Information
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.