Faceting Design Diagram: Crown Star – Tourmaline – Achroite, Dravite, Rubellite, Indicolite, Verdelite, Siberite


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

Crown Star (CHECK14.JRG)Chrysoberyl cut by Tony Carson
By Jeff R. Graham
Copyright 2001
88% Light Return
Angles for R.I. = 1.62
53 facets + 12 facets on girdle = 65
4-fold, mirror-image symmetry
96 index
L/W = 1.000 T/W = 0.373 T/L = 0.373
P/W = 0.442 C/W = 0.180
H/W = (P+C)/W+0.02 = 0.642
P/H = 0.688 C/H = 0.281
Vol./W^3 = 0.259

Addition # 6 – Cut this in refractive indexes 1.62 to 1.92 with no changes. This makes a very bright and sparkly stone. Notice that the pavilion facets P5, P6 are creating a lot of movement.


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.