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

Nigerian Cushion (B12.JRG)
By Jeff R. Graham
Copyright 1999
87.2% Light Return
Angles for R.I. = 1.62
73 facets + 16 facets on girdle = 89
4-fold, mirror-image symmetry
96 index
L/W = 1.000 T/W = 0.534 T/L = 0.534
P/W = 0.477 C/W = 0.179
H/W = (P+C)/W+0.02 = 0.676
P/H = 0.706 C/H = 0.265
Vol./W^3 = 0.263

Addition # 5 - I designed this for some of that large pink Tourmaline that has been coming out of Nigeria. It cuts easy and fairly fast for a Barion. This is best in light to medium color, clean materials. This works well in R.I. 1.62 to 1.76 (89.1%) with no changes. I use this as my default square cushion...

 

 

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