77 Turbo: Faceting Design Diagram

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

77 Turbo (MIR34.JRG)
By Jeff R. Graham
Copyright 2004
93.9% Light Return
Angles for R.I. = 1.62
71 facets + 7 facets on girdle = 78
7-fold, mirror-image symmetry
77 index
L/W = 1.026 T/W = 0.389 T/L = 0.379
P/W = 0.417 C/W = 0.162
H/W = (P+C)/W+0.02 = 0.599
P/H = 0.697 C/H = 0.270
Vol./W^3 = 0.195

Addition # 9 - Cut in refractive indexes 1.62 to 2.14 with no changes. This is bright with a lot of sparkle. It looks like it has thousands of facets. Light to medium saturated stones works well although it is quite nice in a quality Garnet.

Random - Cosine - ISO

Detailed faceting instructions by Jeff Graham available at The Rock Peddler