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

“Streeech” (TLINE24.JRG)
By Jeff R. Graham
Copyright 1998
72% Light Return
Angles for R.I. = 1.62
29 facets + 4 facets on girdle = 33
2-fold, mirror-image symmetry 96 index
L/W = 3.000 T/W = 2.394 T/L = 0.798
P/W = 0.557 C/W = 0.259
H/W = (P+C)/W+0.02 = 0.836
P/H = 0.666 C/H = 0.310
Vol./W^3 = 1.362

Addition # 3 - Cut a 3.0 L/W preform. I get tired of cutting steps in long Tourmaline crystals, so here is what I do. The crown can be cut as low as 32 (subtract 10 from each of the crown tiers). Open "c" is best, 1-18cts.

 

 

 

 

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