Standard Round Brilliant with Unstacked Mains Variation
GemCad Derived Rendering by Bob Keller Bob Keller

SRB Variation with Unstacked Mains
SRB Variation with Unstacked Mains
Angles for R.I. = 1.54 57 facets + 16 facets on girdle = 73
8-fold, mirror-image symmetry 96 index
L/W = 1.000 T/W = 0.477 T/L = 0.477 P/W = 0.466 C/W = 0.218 H/W = (P+C)/W+0.02 = 0.704 P/H = 0.662 C/H = 0.309
Vol./W^3 = 0.236 Brightness at 0 degrees tilt for R.I. = 1.54
COS = 39.1% ISO = 44.2%
Pavilion
pb 45.00 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 43.00 96-12-24-36-48-60-72-84 Cut to meet pb,g
Crown
cb 47.00 03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93 Cut to meet g - level girdle
cm 42.00 06-18-30-42-54-66-78-90 Cut to meet cb,g
s 27.00 96-12-24-36-48-60-72-84 Cut to meet cm,cb
t 0.00 Table Cut to meet s,cm
Another fundamental variation of the SRB 'unstacks' the pavilion and crown main facets, which are cut on the same indexes and 'stacked' in the classic version. This variation has no doubt been accidentally executed more than a few times by faceters who intended to cut the stacked version and somehow got off a cog when they aligned after transferring the stone.


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