Standard Round Brilliant with Highlight Breaks
GemCad Derived Rendering by Bob Keller Bob Keller

SRB Variation with Highlight Breaks
SRB Variation with Highlight Breaks
Angles for R.I. = 1.54 73 facets + 24 facets on girdle = 97
8-fold, mirror-image symmetry 96 index
L/W = 1.000 T/W = 0.508 T/L = 0.508 P/W = 0.450 C/W = 0.154 H/W = (P+C)/W+0.02 = 0.624 P/H = 0.721 C/H = 0.246
Vol./W^3 = 0.205 Brightness at 0 degrees tilt for R.I. = 1.54
COS = 66.5% ISO = 70.8%
Pavilion
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 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 34.50 02-10-14-22-26-34-38-46-50-58-62-70-74-82-86-94 Cut to meet g,cm
ch 36.22 06-18-30-42-54-66-78-90 Cut to meet g,cb
s 18.00 06-18-30-42-54-66-78-90 Cut to meet ch,cb,cm
t 00.00 table Cut to meet s,cm
This variation of the SRB splits 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 increases the scintillation and is one way of adapting or scaling the SRB for use with larger stones.


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