Standard Round Brilliant with Doubled Mains and Stars
GemCad Derived Rendering by Bob Keller
SRB Variation with Doubled Mains and Stars Angles for R.I. = 1.54 81 facets + 16 facets on girdle = 97 16-fold, mirror-image symmetry 96 index L/W = 1.000 T/W = 0.618 T/L = 0.618 P/W = 0.442 C/W = 0.134 H/W = (P+C)/W+0.02 = 0.596 P/H = 0.742 C/H = 0.224 Vol./W^3 = 0.197 Brightness at 0 degrees tilt for R.I. = 1.54
COS = 64.4% ISO = 68.1%
Pavilion pb 42.50 03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93 Cut to temporary center point g 90.00 03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93 Cut to meet pb pm 41.50 96-06-12-18-24-30-36-42-48-54-60-66-72-78-84-90 Cut to meet pb,g Crown cb 38.00 03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93 Cut to meet g - level girdle cm 35.00 96-06-12-18-24-30-36-42-48-54-60-66-72-78-84-90 Cut to meet cb,g s 27.00 03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93 Cut to meet cb,cm t 0.00 Table Cut to meet s,cm This variation of the SRB doubles the number of main and star facets in each course. Note that in this variation the symmetry increases from 8 fold to 16 fold - there are 16 each pavilion main, pavilion break, girdle, crown break, crown main and star facets. 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 Doubled Mains and Stars Design File is available for GemCad users.