Faceting Design Diagram: Montana Burst – Sapphire / Corundum – Ruby, Ceylon, Padparadschah, Pink, Yellow, Green


Sapphire / Corundum (Ruby, Ceylon, Padparadschah, Pink, Yellow, Green)

Montana Burst (SAP10.JRG)
By Jeff R. Graham
Copyright 1995
80.2% Light Return
Angles for R.I. = 1.76
57 facets + 8 facets on girdle = 65
8-fold, mirror-image symmetry
96 index
L/W = 1.000 T/W = 0.503 T/L = 0.503
P/W = 0.405 C/W = 0.199
H/W = (P+C)/W+0.02 = 0.624
P/H = 0.649 C/H = 0.318
Vol./W^3 = 0.238

Gram Book 1 – I designed this cut for some nice roundish Montana material that I bought. It cuts easy and makes a nice 1ct+ stone. Cut the steps on the crown to your taste, varied widths are better, I think. Cut in refractive index 1.78 to 1.93 (80.1%) with no 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.