OPLC Faceters Companion

Standard Round Brilliant with Horizontally Split Mains
GemCad Derived Rendering by Bob Keller

SRB Variation with Horizontally Split Mains

Angles for R.I. = 1.54 73 facets + 16 facets on girdle = 89

8-fold, mirror-image symmetry 96 index

L/W = 1.000 T/W = 0.528 T/L = 0.528 P/W = 0.487 C/W = 0.172 H/W = (P+C)/W+0.02 = 0.680 P/H = 0.717 C/H = 0.253

Vol./W^3 = 0.227 Brightness at 0 degrees tilt for R.I. = 1.54
COS = 34.7% ISO = 38.2%

Pavilion

pb 47.00 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

pm1 45.00 96-12-24-36-48-60-72-84 Cut to meet pb,g

pm2 43.00 96-12-24-36-48-60-72-84 Cut to meet pb, pm1

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

cm1 38.00 96-12-24-36-48-60-72-84 Cut to meet cb,g

cm2 34.00 96-12-24-36-48-60-72-84 Cut to meet cb,cm1

s 25.00 06-18-30-42-54-66-78-90 Cut to meet cb,cm1,cm2

t 0.00 Table Cut to meet s,cm2

This variation of the SRB doubles the number of main facets from 8 to 16 by splitting them horizontally with the pairs of mains cut at the same index but different angles. The mains can be split on the pavilion only, crown only, or both. Adding more facets by splitting the mains increases the scintillation and is one way of adapting or scaling the SRB for use with larger stones.

The SRB Variation with Horizontally Split Mains Design File is available for GemCad users.

SRB Variation with Horizontally Split Mains
Angles for R.I. = 1.54	73 facets + 16 facets on girdle = 89
8-fold, mirror-image symmetry	96 index
L/W = 1.000 T/W = 0.528 T/L = 0.528 P/W = 0.487 C/W = 0.172	H/W = (P+C)/W+0.02 = 0.680 P/H = 0.717 C/H = 0.253
Vol./W^3 = 0.227	Brightness at 0 degrees tilt for R.I. = 1.54 COS = 34.7% ISO = 38.2%

Pavilion
pb	47.00	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
pm1	45.00	96-12-24-36-48-60-72-84	Cut to meet pb,g
pm2	43.00	96-12-24-36-48-60-72-84	Cut to meet pb, pm1
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
cm1	38.00	96-12-24-36-48-60-72-84	Cut to meet cb,g
cm2	34.00	96-12-24-36-48-60-72-84	Cut to meet cb,cm1
s	25.00	06-18-30-42-54-66-78-90	Cut to meet cb,cm1,cm2
t	0.00	Table	Cut to meet s,cm2
This variation of the SRB doubles the number of main facets from 8 to 16 by splitting them horizontally with the pairs of mains cut at the same index but different angles. The mains can be split on the pavilion only, crown only, or both. Adding more facets by splitting the mains increases the scintillation and is one way of adapting or scaling the SRB for use with larger stones.

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