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

Boxed (TLINE20.JRG)
By Jeff R. Graham
Copyright 1995
81.5% Light Return
Angles for R.I. = 1.62
43 facets + 8 facets on girdle = 51
2-fold, mirror-image symmetry
96 index
L/W = 1.203 T/W = 0.525 T/L = 0.436
P/W = 0.454 C/W = 0.269
H/W = (P+C)/W+0.02 = 0.743
P/H = 0.611 C/H = 0.362
Vol./W^3 = 0.379

Gram Book 1 - It helps if you cut in a temporary girdle P4(G) and P6(G)in a preform L/W=1.20 rectangle. Then cut P1,P2,P3 to center point and adjust the girdle if need be. The P8's cut fast, light to medium material 1-6cts. Cut in refractive index 1.62 to 1.76 (85%) with no changes.

 

 

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