All facets of these cuts may be divided into types, or layers: table, star facets, main crown facets (also known as bezel facets), upper girdle facets, lower girdle facets (also known as halves), and main pavilion facets.
A stone is positioned in the standard orientation, that is, with its table horizontal and facing downwards. Slope and azimuth angles are calculated and reported for each facet. The facets are grouped by types and ordered by azimuth within each type.
Azimuth is measured in the range from 0 to 360 degrees. Slope is measured in the range from 0 to 90 degrees. Table facet has zero slope by definition.
There are 56 slopes and as much azimuths in a round brilliant cut. Other cuts may vary in this regard.
Star Angle
This is the slope angle of the star facets.
Star Angle (symmetry)
Star Angle (symmetry) is defined as the maximum difference of Star Angle measurements, i.e. the same as deviation of Star Angle value. As all symmetry parameters, it is an estimate of a deviation from perfect symmetry, and should be zero for an ideal stone.
Reporting
Reported in | Section | Values | Units | Bookmarks |
---|---|---|---|---|
Full Report for Brilliant, | Main Parameters | Avg, Min, Max, Dev | ° |
|
Detailed Parameters | All 8 values | ° |
|
Crown Angle
This is the slope angle of the main crown facets.
Crown Angle (symmetry)
Crown Angle (symmetry) is defined as the maximum difference of Crown Angle measurements, i.e. the same as deviation of Crown Angle value. As all symmetry parameters, it is an estimate of a deviation from perfect symmetry, and should be zero for an ideal stone.
Reporting
Reported in | Section | Values | Units | Bookmarks |
---|---|---|---|---|
| Main Parameters | Avg, Min, Max, Dev | ° |
|
Detailed Parameters | All 8 values | ° |
|
Crown Slope
The slope angle of facets, marked in Facet Types as "Crown - Main":
Calculation
CROWN_ANGLE_DEG_DEV = CROWN_ANGLE_DEG_MAX - CROWN_ANGLE_DEG_MIN
Usage and Examples
Used to control and estimate the slope of crown main facets. Grades example for appraiser "CushionSquare", Profile "Cushion2-Optimized" as on Apr 22, 2021:
For Crown Slope Avg, ° (CROWN_ANGLE_DEG) |
For Crown Slope Dev, ° (CROWN_ANGLE_DEG_DEV) |
Reporting
Reported in | Section | Values | Units | Bookmarks | Name in Report |
---|---|---|---|---|---|
Full Report for Square Cushion | Main Parameters | Avg Min Max Dev | ° | CROWN_ANGLE_DEG | Crown Main angle |
Detailed Parameters | 1, 2, 3, 4 | ° | CROWN_ANGLE_DEG_1, ..., CROWN_ANGLE_DEG_4 | Crown Main angle | |
Illustrated Report for Square Cushion, Standard Report, I3D Report | Parameter | Avg, Min, Max, Dev, 1-4 | ° | The same | Crown angle, ° |
Visualization in Appraisers
Appraiser | Tab | Parameter Name | Value | Units | Bookmark | Comment |
---|---|---|---|---|---|---|
CushionSquare | Absolute Cut | CrownSlope | Avg | ° | CROWN_ANGLE_DEG | |
Absolute Symmetry | CrownSlope | Dev | ° | CROWN_ANGLE_DEG_DEV | ||
Relative Cut | CrownSlope | Single Value | ° | NA | How far from the allocation form (= Reference) the Avg value deviates. | |
Relative Symmetry | CrownSlope | Single Value | ° | NA | How far from the allocation form (= Reference) the Dev value deviates. |
Crown Slope (Width and Length)
The slope angle of facets, marked in Facet Types as "Crown - Main - Width" and "Crown - Main - Length":
Calculation
CRN_MAIN_[WIDTH or LENGTH]_ANGLE_DEG_DEV = CRN_MAIN_[WIDTH or LENGTH]_ANGLE_DEG_MAX - CRN_MAIN_[WIDTH or LENGTH]_ANGLE_DEG_MIN
Usage and Examples
Used to control and estimate the slope of crown main facets along the width and length. Grades example for appraiser "CushionRectangular", Profile "Cushion1" as of May 13, 2021:
For Avg, ° (CRN_MAIN_[WIDTH or LENGTH]_ANGLE_DEG_AVG) |
For Dev, ° (CRN_MAIN_[WIDTH or LENGTH]_ANGLE_DEG_DEV) |
Reporting
Reported in | Section | Values | Units | Bookmarks | Name in Report |
---|---|---|---|---|---|
Full Report for Cushion | Main Parameters | Avg Min Max Dev | ° | CRN_MAIN_[WIDTH or LENGTH]_ANGLE_DEG_AVG | Crown Main Width angle |
Detailed Parameters | 1, 2 | ° | CRN_MAIN_[WIDTH or LENGTH]_ANGLE_DEG_1, CRN_MAIN_[WIDTH or LENGTH]_ANGLE_DEG_2 | Crown Main Width angle Crown Main Length angle | |
Illustrated Report for Cushion | Parameters | Avg, Min, Max, Dev, 1-2 | ° | The same | Crn Main Width ang, ° Crn Main Length ang, ° |
Standard Report, I3D Report | Parameter | Avg, Min, Max, Dev, 1-2 | ° | The same | Crown Main Width angle, ° Crown Main Length angle, ° |
Visualization in Appraisers
Appraiser | Tab | Parameter Name | Value | Units | Bookmark | Comment |
---|---|---|---|---|---|---|
CushionRectangular | Absolute Cut | CrownWidthSlope CrownLengthSlope | Avg | ° | CRN_MAIN_[WIDTH or LENGTH]_ANGLE_DEG_AVG | |
Absolute Symmetry | CrownWidthSlope CrownLengthSlope | Dev | ° | CRN_MAIN_[WIDTH or LENGTH]_ANGLE_DEG_DEV | ||
Relative Cut | CrownWidthSlope CrownLengthSlope | Single Value | ° | NA | How far from the allocation form (= Reference) the Avg value deviates. | |
Relative Symmetry | CrownWidthSlope CrownLengthSlope | Single Value | ° | NA | How far from the allocation form (= Reference) the Dev value deviates. |
Upper Girdle Angle
This is the slope angle of the upper girdle facets.
Upper Girdle Angle (symmetry)
Upper Girdle Angle (symmetry) is defined as the maximum difference of Upper Girdle Angle measurements, i.e. the same as deviation of Upper Girdle Angle value. As all symmetry parameters, it is an estimate of a deviation from perfect symmetry, and should be zero for an ideal stone.
Reporting
Reported in | Section | Values | Units | Bookmarks |
---|---|---|---|---|
Full Report for Brilliant, | Main Parameters | Avg, Min, Max, Dev | ° |
|
Detailed Parameters | All 16 values | ° |
|
Lower Girdle Angle
This is the slope angle of the lower girdle facets.
Lower Girdle Angle (symmetry)
Lower Girdle Angle (symmetry) is defined as the maximum difference of Lower Girdle Angle measurements, i.e. the same as deviation of Lower Girdle Angle value. As all symmetry parameters, it is an estimate of a deviation from perfect symmetry, and should be zero for an ideal stone.
Reporting
Reported in | Section | Values | Units | Bookmarks |
---|---|---|---|---|
Full Report for Brilliant, | Main Parameters | Avg, Min, Max, Dev | ° |
|
Detailed Parameters | All 16 values | ° |
|
Pavilion Angle
This is the slope angle of the main pavilion facets.
Pavilion Angle (symmetry)
Pavilion Angle (symmetry) is defined as the maximum difference of Pavilion Angle measurements, i.e. the same as deviation of Pavilion Angle value. As all symmetry parameters, it is an estimate of a deviation from perfect symmetry, and should be zero for an ideal stone.
Reporting
Reported in | Section | Values | Units | Bookmarks |
---|---|---|---|---|
| Main Parameters | Avg, Min, Max, Dev | ° |
|
Detailed Parameters | All 8 values | ° |
|
Star Facets Azimuth
This is the azimuth angle of the star facets.
Reporting
Reported in | Section | Values | Units | Bookmarks |
---|---|---|---|---|
| Main Parameters | Dev (Deviation from ideal) (only for brilliant) | ° |
|
Detailed Parameters | All 8 values | ° |
| |
Detailed Parameters | Deviations from ideal (only for brilliant) | ° |
|
Crown Facets Azimuth
This is the azimuth angle of the main crown facets.
Reporting
Reported in | Section | Values | Units | Bookmarks |
---|---|---|---|---|
Full Report for Brilliant | Detailed Parameters | All 8 values | ° |
|
Deviations from ideal | ° | CROWN_AZIMUTH_DEV_IDEAL_DEG_1, ..., CROWN_AZIMUTH_DEV_IDEAL_DEG_8 |
Note that the standard orientation of brilliant is defined via the first crown facet having zero azimuth, hence CROWN_ANGLE_AZIMUTH_DEG_1
and CROWN_AZIMUTH_DEV_IDEAL_DEG_1
always equal 0.00°.
Upper Girdle Facets Azimuth
This is the azimuth angle of the upper girdle facets.
Reporting
Reported in | Section | Values | Units | Bookmarks |
---|---|---|---|---|
| Detailed Parameters | All 16 values | ° |
|
Deviations from ideal (only for brilliant) | ° | UPPER_AZIMUTH_DEV_IDEAL_DEG_1, ..., UPPER_AZIMUTH_DEV_IDEAL_DEG_16 |
Lower Girdle Facets Azimuth
This is the azimuth angle of the lower girdle facets.
Reporting
Reported in | Section | Values | Units | Bookmarks |
---|---|---|---|---|
| Detailed Parameters | All 16 values | ° |
|
Deviations from ideal (only for brilliant) | ° | HALVES_AZIMUTH_DEV_IDEAL_DEG_1, ..., HALVES_AZIMUTH_DEV_IDEAL_DEG_16 |
Pavilion Facets Azimuth
This is the azimuth angle of the main pavilion facets.
Reporting
Reported in | Section | Values | Units | Bookmarks |
---|---|---|---|---|
Full Report for Brilliant | Detailed Parameters | All 8 values | ° |
|
Deviations from ideal | ° |
|
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