Faceting Design Diagram: Opposed Bar 1.50 – Tourmaline – Achroite, Dravite, Rubellite, Indicolite, Verdelite, Siberite


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

Opposed Bar 1.50 (MC22.JRG) 12.58 carat bi-color Tourmaline
By Jeff R. Graham
Copyright 1999
88.4% Light Return
Angles for R.I. = 1.62
17 facets + 8 facets on girdle = 25
2-fold, mirror-image symmetry
96 index
L/W = 1.500 T/W = 0.862 T/L = 0.575
P/W = 0.482 C/W = 0.212
H/W = (P+C)/W+0.02 = 0.714
P/H = 0.675 C/H = 0.297
Vol./W^3 = 0.634

Addition # 4 – This cut easy and can be almost any L/W with no changes. It works well in Tourmaline that is dark or closed on the “c” axis. You can cut the corners in or leave them pointed, 1cts and up… NOTE: P5 is optional. Cut this in R.I. 1.62 to 1.76 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.