OPLC Faceters Companion

Standard Round Brilliant with Apex Facets Replacing Table
GemCad Derived Rendering by Bob Keller

SRB Variation with Apex Facets Replacing Table

Angles for R.I. = 1.54 64 facets + 16 facets on girdle = 80

8-fold, mirror-image symmetry 96 index

L/W = 1.000 P/W = 0.405 C/W = 0.155 H/W = (P+C)/W+0.02 = 0.580 P/H = 0.698 C/H = 0.268

Vol./W^3 = 0.180 Brightness at 0 degrees tilt for R.I. = 1.54
COS = 88.4% ISO = 93.8%

Pavilion

pb 41.00 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 39.00 96-12-24-36-48-60-72-84 Cut to meet pb,g

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 28.00 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

a 10.00 06-18-30-42-54-66-78-90 Cut to meet s,cm

This variation of the SRB replaces the table with apex facets. Apex facets are smaller and easier to polish on larger stones. The angled apex facets refract incident light at a different angle internally than a 0° table, allowing further reduction in the angles of the pavilion facets to values that would dump light and 'fisheye' or 'window' with a conventional table. Note the brightness figures for this variation and angles employed.

The SRB with Apex Facets Design File is available for GemCad users.

SRB Variation with Apex Facets Replacing Table
Angles for R.I. = 1.54	64 facets + 16 facets on girdle = 80
8-fold, mirror-image symmetry	96 index
L/W = 1.000 P/W = 0.405 C/W = 0.155	H/W = (P+C)/W+0.02 = 0.580 P/H = 0.698 C/H = 0.268
Vol./W^3 = 0.180	Brightness at 0 degrees tilt for R.I. = 1.54 COS = 88.4% ISO = 93.8%

Pavilion
pb	41.00	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	39.00	96-12-24-36-48-60-72-84	Cut to meet pb,g
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	28.00	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
a	10.00	06-18-30-42-54-66-78-90	Cut to meet s,cm
This variation of the SRB replaces the table with apex facets. Apex facets are smaller and easier to polish on larger stones. The angled apex facets refract incident light at a different angle internally than a 0° table, allowing further reduction in the angles of the pavilion facets to values that would dump light and 'fisheye' or 'window' with a conventional table. Note the brightness figures for this variation and angles employed.

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