Faceting Design Diagram: Diamond “C” – Garnet – Pyrope, Rhodolite, Almandine, Spessartite, Grossular, Demantoid, Tsavorite

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

Diamond “C” (GNETP29.JRG)
By Jeff R. Graham
Copyright 1996
90.3% Light Return
Angles for R.I. = 1.73
57 facets + 10 facets on girdle = 67
2-fold, mirror-image symmetry
96 index
L/W = 1.290 T/W = 0.557 T/L = 0.432
P/W = 0.406 C/W = 0.189
H/W = (P+C)/W+0.02 = 0.614
P/H = 0.660 C/H = 0.307
Vol./W^3 = 0.305

Gram Book 1 – This is a little tough to cut, but well worth it. The P7 & P9 meet at an apex and might need to be cheated a little bit. As long as they are close the P10 will cover them, good for darker material, 2-12cts. This works in man-made Sapphire and Spinel.

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.