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Standard Round Brilliant with 12 Fold Symmetry
GemCad Derived Rendering by Bob Keller

SRB Variation with 12 Fold Symmetry
SRB Variation with 12 Fold Symmetry
Angles for R.I. = 1.54 85 facets + 24 facets on girdle = 109
12-fold, mirror-image symmetry 96 index
L/W = 1.000 T/W = 0.603 T/L = 0.603 P/W = 0.450 C/W = 0.139 H/W = (P+C)/W+0.02 = 0.609 P/H = 0.739 C/H = 0.228
Vol./W^3 = 0.203 Brightness at 0 degrees tilt for R.I. = 1.54
COS = 62.8% ISO = 66.3%
Pavilion
pb 43.00 02-06-10-14-18-22-26-30-34-38-42-46-
50-54-58-62-66-70-74-78-82-86-90-94
Cut to temporary center point
g 90.00 02-06-10-14-18-22-26-30-34-38-42-46-
50-54-58-62-66-70-74-78-82-86-90-94
Cut to meet pb
pm 42.00 96-08-16-24-32-40-48-56-64-72-80-88 Cut to meet pb,g
Crown
cb 37.00 02-06-10-14-18-22-26-30-34-38-42-46-
50-54-58-62-66-70-74-78-82-86-90-94
Cut to meet g - level girdle
cm 35.00 96-08-16-24-32-40-48-56-64-72-80-88 Cut to meet cb,g
s 18.00 04-12-20-28-36-44-52-60-68-76-84-92 Cut to meet cb,cm
t 0.00 Table Cut to meet s,cm
This variation of the SRB increases the number of facets in each course by 50% by increasing the symmetry from 8 fold to 12 fold. Increasing the number of facets increases the scintillation and is a way of scaling up the SRB to work with larger stones.

The SRB with 12 Fold Symmetry File is available for GemCad users.

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