Faceting Design Diagram: Shadow Box Triangle – Garnet – Pyrope, Rhodolite, Almandine, Spessartite, Grossular, Demantoid, Tsavorite

Garnet (Pyrope, Rhodolite, Almandine, Spessartite, Grossular, Demantoid, Tsavorite)

Shadow Box Triangle (GNETA4.JRG)
By Jeff R. Graham
Copyright 1993
80% Light Return
Angles for R.I. = 1.78
46 facets + 9 facets on girdle = 55
3-fold, mirror-image symmetry
96 index
L/W = 1.012 T/W = 0.312 T/L = 0.308
P/W = 0.416 C/W = 0.187
H/W = (P+C)/W+0.02 = 0.622
P/H = 0.668 C/H = 0.300
Vol./W^3 = 0.210

Gram Book 1 – This design is a little harder to cut (like most triangles), but it has much better return than any other that I’ve ever seen (notice the 1.78 R.I.). Most only have return in the center none in edges. Light to med material this works well in YAG, Sapphire and Spinel, 1-12cts.

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.