Facets' slopes and azimuth angles

These parameters are applicable to the following cuts: Round brilliant, Marquise, Oval, Pear, Heart.

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.

This is the slope angle of the star facets.

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.

Reported in	Section	Values	Units	Bookmarks
Full Report for Brilliant, Full Report for Rounded Fancies	Main Parameters	Avg, Min, Max, Dev	°	`STAR_ANGLE_DEG, STAR_ANGLE_DEG_MIN, STAR_ANGLE_DEG_MAX, STAR_ANGLE_DEG_DEV`
Full Report for Brilliant, Full Report for Rounded Fancies	Detailed Parameters	All 8 values	°	`STAR_ANGLE_DEG_1, ..., STAR_ANGLE_DEG_8`

This is the slope angle of the main crown facets.

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.

Reported in	Section	Values	Units	Bookmarks
Full Report for Brilliant	Main Parameters	Avg, Min, Max, Dev	°	`CROWN_ANGLE_DEG, CROWN_ANGLE_DEG_MIN, CROWN_ANGLE_DEG_MAX, CROWN_ANGLE_DEG_DEV`
Full Report for Brilliant	Detailed Parameters	All 8 values	°	`CROWN_ANGLE_DEG_1, ..., CROWN_ANGLE_DEG_8`

This parameter is applicable to the following cuts: Cushion Square.

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_ANGLE_DEG_MIN CROWN_ANGLE_DEG_MAX CROWN_ANGLE_DEG_DEV	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.

These parameters are applicable to the following cuts: Cushion Rectangular.

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 CRN_MAIN_[WIDTH or LENGTH]_ANGLE_DEG_MIN CRN_MAIN_[WIDTH or LENGTH]_ANGLE_DEG_MAX CRN_MAIN_[WIDTH or LENGTH]_ANGLE_DEG_DEV	Crown Main Width angle Crown Main Length 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.

This is the slope angle of the upper girdle facets.

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.

Reported in	Section	Values	Units	Bookmarks
Full Report for Brilliant, Full Report for Rounded Fancies	Main Parameters	Avg, Min, Max, Dev	°	`UPPER_ANGLE_DEG, UPPER_ANGLE_DEG_MIN, UPPER_ANGLE_DEG_MAX, UPPER_ANGLE_DEG_DEV`
Full Report for Brilliant, Full Report for Rounded Fancies	Detailed Parameters	All 16 values	°	`UPPER_ANGLE_DEG_1, ..., UPPER_ANGLE_DEG_16`

This is the slope angle of the lower girdle facets.

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.

Reported in	Section	Values	Units	Bookmarks
Full Report for Brilliant, Full Report for Rounded Fancies	Main Parameters	Avg, Min, Max, Dev	°	`HALVES_ANGLE_DEG, HALVES_ANGLE_DEG_MIN, HALVES_ANGLE_DEG_MAX, HALVES_ANGLE_DEG_DEV`
Full Report for Brilliant, Full Report for Rounded Fancies	Detailed Parameters	All 16 values	°	`HALVES_ANGLE_DEG_1, ..., HALVES_ANGLE_DEG_16`

This is the slope angle of the main pavilion facets.

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.

Reported in	Section	Values	Units	Bookmarks
Full Report for Brilliant	Main Parameters	Avg, Min, Max, Dev	°	`PAVILION_ANGLE_DEG, PAVILION_ANGLE_DEG_MIN, PAVILION_ANGLE_DEG_MAX, PAVILION_ANGLE_DEG_DEV`
Full Report for Brilliant	Detailed Parameters	All 8 values	°	`PAVILION_ANGLE_DEG_1, ..., PAVILION_ANGLE_DEG_8`

This is the azimuth angle of the star facets.

Reported in	Section	Values	Units	Bookmarks
Full Report for Brilliant, Full Report for Rounded Fancies	Main Parameters	Dev (Deviation from ideal) (only for brilliant)	°	`STAR_FACET_AZIMUTH_SYM_DEG`
	Detailed Parameters	All 8 values	°	`STAR_ANGLE_AZIMUTH_DEG_1, ..., STAR_ANGLE_AZIMUTH_DEG_8`
	Detailed Parameters	Deviations from ideal (only for brilliant)	°	`STAR_AZIMUTH_DEV_IDEAL_DEG_1, ..., STAR_AZIMUTH_DEV_IDEAL_DEG_8`

This is the azimuth angle of the main crown facets.

Reported in	Section	Values	Units	Bookmarks
Full Report for Brilliant	Detailed Parameters	All 8 values	°	`CROWN_ANGLE_AZIMUTH_DEG_1, ..., CROWN_ANGLE_AZIMUTH_DEG_8`
Full Report for Brilliant	Detailed Parameters	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°.

This is the azimuth angle of the upper girdle facets.

Reported in	Section	Values	Units	Bookmarks
Full Report for Brilliant, Full Report for Rounded Fancies	Detailed Parameters	All 16 values	°	`UPPER_ANGLE_AZIMUTH_DEG_1, ..., UPPER_ANGLE_AZIMUTH_DEG_16`
Full Report for Brilliant, Full Report for Rounded Fancies	Detailed Parameters	Deviations from ideal (only for brilliant)	°	`UPPER_AZIMUTH_DEV_IDEAL_DEG_1, ..., UPPER_AZIMUTH_DEV_IDEAL_DEG_16`

This is the azimuth angle of the lower girdle facets.

Reported in	Section	Values	Units	Bookmarks
Full Report for Brilliant, Full Report for Rounded Fancies	Detailed Parameters	All 16 values	°	`HALVES_ANGLE_AZIMUTH_DEG_1, ..., HALVES_ANGLE_AZIMUTH_DEG_16`
Full Report for Brilliant, Full Report for Rounded Fancies	Detailed Parameters	Deviations from ideal (only for brilliant)	°	`HALVES_AZIMUTH_DEV_IDEAL_DEG_1, ..., HALVES_AZIMUTH_DEV_IDEAL_DEG_16`

This is the azimuth angle of the main pavilion facets.

Reported in	Section	Values	Units	Bookmarks
Full Report for Brilliant	Detailed Parameters	All 8 values	°	`PAVILION_ANGLE_AZIMUTH_DEG_1, ..., PAVILION_ANGLE_AZIMUTH_DEG_8`
Full Report for Brilliant	Detailed Parameters	Deviations from ideal	°	`PAVILION_AZIMUTH_DEV_IDEAL_DEG_1, ..., PAVILION_AZIMUTH_DEV_IDEAL_DEG_8`

Page tree

Star Angle

Star Angle (symmetry)

Reporting

Crown Angle

Crown Angle (symmetry)

Reporting

Crown Slope

Crown Slope (Width and Length)

Upper Girdle Angle

Upper Girdle Angle (symmetry)

Reporting

Lower Girdle Angle

Lower Girdle Angle (symmetry)

Reporting

Pavilion Angle

Pavilion Angle (symmetry)

Reporting

Star Facets Azimuth

Reporting

Crown Facets Azimuth

Reporting

Upper Girdle Facets Azimuth

Reporting

Lower Girdle Facets Azimuth

Reporting

Pavilion Facets Azimuth

Reporting