Faceting Design Diagram: “B” Oval – Tourmaline – Achroite, Dravite, Rubellite, Indicolite, Verdelite, Siberite


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

“B” Oval (B6.JRG)
By Jeff R. Graham
Copyright 1999
80% Light Return
Angles for R.I. = 1.62
81 facets + 16 facets on girdle = 97
2-fold, mirror-image symmetry
96 index
L/W = 1.303 T/W = 0.762 T/L = 0.585
P/W = 0.588 C/W = 0.199
H/W = (P+C)/W+0.02 = 0.807
P/H = 0.728 C/H = 0.247
Vol./W^3 = 0.402

Addition # 5 – The breaks are high, but this should be easy to set on the short ends. Cut to center point, then girdle to meet P1, then breaks. Cut in R.I 1.62 to 1.76 (89.4%) with no changes, light material is best.

 


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.