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

Scribe Triangle (TLINE4.JRG)
By Jeff R. Graham Copyright 1993
79.1% Light Return
Angles for R.I. = 1.62
49 facets + 9 facets on girdle = 58
3-fold, mirror-image symmetry
96 index
L/W = 1.020 T/W = 0.360 T/L = 0.353
P/W = 0.424 C/W = 0.182
H/W = (P+C)/W+0.02 = 0.625
P/H = 0.677 C/H = 0.291
Vol./W^3 = 0.207

Gram Book 1 - Cut this design in medium to light material. A larger size stone works best because of the narrow crown facets. It cuts easy and fast for a triangle, and has nice sparkle, 1-12cts. Cut in refractive index 1.62 to 1.76 (79.4%) with no changes.

 

 

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