OPLC Faceters Companion

Standard Round Brilliant with Pavilion Step at Girdle
GemCad Derived Rendering by Bob Keller

SRB Variation - Mixed Cut with Pavilion Step at Girdle

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 = 0.529 T/L = 0.529 P/W = 0.578 C/W = 0.136 H/W = (P+C)/W+0.02 = 0.734 P/H = 0.788 C/H = 0.185

Vol./W^3 = 0.271 Brightness at 0 degrees tilt for R.I. = 1.54
COS = 59.4% ISO = 63.2%

Pavilion

pb1 44.00 03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93 Cut to temporary center point

pb2 65.00 03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93 Cut to meet pb1

g 90.00 03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93 Cut to meet pb2

pm1 42.00 96-12-24-36-48-60-72-84 Cut to meet pb1,pb2

Crown

cb 34.00 03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93 Cut to meet g - level girdle

cm 30.00 96-12-24-36-48-60-72-84 Cut to meet cb,g

s 15.00 06-18-30-42-54-66-78-90 Cut to meet cb,cm

t 0.00 Table Cut to meet s,cm

This variation of the SRB adds a course of trapezoidal, relatively steep, step cut facets between the girdle and the triangular shaped pavilion break facets. It is considered to be a mixed cut, combining both step and brilliant cut facets. This cut can be useful for increasing yield and color saturation if you have deep rough. Steeper angles on the step cut will produce a brighter stone, but mounting practicalities generally dictate against extreme step angles.

The SRB with Pavilion Step at Girdle Design File is available for GemCad users.

SRB Variation - Mixed Cut with Pavilion Step at Girdle
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 = 0.529 T/L = 0.529 P/W = 0.578 C/W = 0.136	H/W = (P+C)/W+0.02 = 0.734 P/H = 0.788 C/H = 0.185
Vol./W^3 = 0.271	Brightness at 0 degrees tilt for R.I. = 1.54 COS = 59.4% ISO = 63.2%

Pavilion
pb1	44.00	03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93	Cut to temporary center point
pb2	65.00	03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93	Cut to meet pb1
g	90.00	03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93	Cut to meet pb2
pm1	42.00	96-12-24-36-48-60-72-84	Cut to meet pb1,pb2
Crown
cb	34.00	03-09-15-21-27-33-39-45-51-57-63-69-75-81-87-93	Cut to meet g - level girdle
cm	30.00	96-12-24-36-48-60-72-84	Cut to meet cb,g
s	15.00	06-18-30-42-54-66-78-90	Cut to meet cb,cm
t	0.00	Table	Cut to meet s,cm
This variation of the SRB adds a course of trapezoidal, relatively steep, step cut facets between the girdle and the triangular shaped pavilion break facets. It is considered to be a mixed cut, combining both step and brilliant cut facets. This cut can be useful for increasing yield and color saturation if you have deep rough. Steeper angles on the step cut will produce a brighter stone, but mounting practicalities generally dictate against extreme step angles.

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