Standard Round Brilliant with Highlight Breaks and Stars
GemCad Derived Rendering by Bob Keller
SRB Variation with Highlight Breaks and Stars Angles for R.I. = 1.54 89 facets + 24 facets on girdle = 113 8-fold, mirror-image symmetry 96 index L/W = 1.000 T/W = 0.592 T/L = 0.592 P/W = 0.450 C/W = 0.128 H/W = (P+C)/W+0.02 = 0.598 P/H = 0.753 C/H = 0.213 Vol./W^3 = 0.199 Brightness at 0 degrees tilt for R.I. = 1.54
COS = 69.9% ISO = 73.6%
Pavilion g 90.00 02-06-10-14-18-22-26-30-34-38-42-46-
Cut to equal depth, establish size pm 42.00 96-12-24-36-48-60-72-84 Cut to equal depth, establish girdle pb 43.00 02-10-14-22-26-34-38-46-50-58-62-70-74-82-86-94 Meet g,pm ph 43.53 06-18-30-42-54-66-78-90 Meet g,pb,pm Crown cm 32.00 96-12-24-36-48-60-72-84 Cut to equal depth - establish upper girdle line cb 35.50 02-10-14-22-26-34-38-46-50-58-62-70-74-82-86-94 Cut to meet g,cm ch 38.09 06-18-30-42-54-66-78-90 Cut to meet g,cb s 24.00 02-10-14-22-26-34-38-46-50-58-62-70-74-82-86-94 Cut to meet ch,cb,cm sh 20.60 06-18-30-42-54-66-78-90 Cut to meet s,ch,cb,cm t 00.00 table Cut to meet s,cm This variation 'highlights' the stars of the SRB in addition to splitting the break facets with a third facet instead of a single dividing ridge. Note there are 24 equal girdle segments in this variation instead of the usual 16 with an 8-fold symmetry SRB. Adding more facets by "fanning out" the breaks and stars increases the scintillation and is one way of adapting or scaling the SRB for use with larger stones.
The SRB with Highlight Breaks and Stars Design File is available for GemCad users.