77 Turbo: Faceting Design Diagram
Detailed information and guide on Faceting Designs. A Faceting Design Diagram by Jeff R. Graham that presents various cuts, this one is called "77 Turbo"
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
Jeff R. Graham
The late Jeff Graham was a prolific faceter, creator of many original faceting designs, and the author of several highly-regarded instructional faceting books such as Gram Faceting Designs.
Related Articles
Tourmaline Value, Price, and Jewelry Information
A Look at African Paraíba Tourmaline Rough
Tourmaline Buying Guide
What is the Usambara Effect In Gemstones?
Never Stop Learning
When you join the IGS community, you get trusted diamond & gemstone information when you need it.
Get Gemology Insights
Get started with the International Gem Society’s free guide to gemstone identification. Join our weekly newsletter & get a free copy of the Gem ID Checklist!