Applicable to:

• Brilliants
• Rounded Fancies / Marquise, Oval, Pear
• Rectangular Fancies / Princess, Radiant
• StepCuts
• Unknown cuts

Parameters Girdle-Table offset by table axis, Girdle-Culet offset by table axis, Table-Culet offset by table axis are values in mm and % from average diameter or width with possible error:    

Girdle-Culet offset by table axis	1.20 ± 0.30, %	0.048 ± 0.012, mm
Girdle-Table offset by table axis	0.63 ± 0.28, %	0.025 ± 0.011, mm
Table-Culet offset by table axis	1.21 ± 0.32, %	0.048 ± 0.013, mm

Program measures offsets as distance between normals from centers of table (or girdle or culet) by table axis. For example, Girdle-Table offset by table axis is distance between normal lying from girdle center by table and table center.

Illustrations of crown view and pavilion view have images of table center, girdle center and table center for visualization of described above parameters.

*Diameter of circle on image Girdle center is equal 2% from average stone diameter to visual estimation of symmetry and distance between table, girdle and culet centers.

Estimation Girdle, Table and Culet centers for different cuts

Brilliant

• Girdle center - center of maximum inscribed center (MIC)
• Table center - table centre of mass
• Culet center:
  • if culet has facets - culet center is its center of mass
  • else culet center is maximum height point

Rounded Fancies

• Girdle center - first created perpendicular to the center of maximum diameter. The center of the parallel to the perpendicular diameter is girdle center.
• Table center - table centre of mass
• Culet center:
  • if culet has facets - culet center is its center of mass
  • else culet center is maximum height point

Rectangular Fancies

• Girdle center - at the intersection of diagonals
• Table center - table centre of mass
• Culet center:
  • if culet has facets - culet center is its center of mass
  • else culet center is maximum height point

StepCuts

• Girdle center - at the intersection of diagonals from opposite corners. First diagonal is maximum diameter. Second is the vertical mirror symmetry to first diagonal.
• Table center - table centre of mass
• Culet center - если удлинение больше, чем 1.1, то это середина верхнего отрезка, иначе, if culet has facets - culet center is its center of mass, else culet center is maximum height point
• Culet center:
  • if there is a culet segment with lengthening 1.1, culet center is the segment center
  • else if culet has facets - culet center is its center of mass
  • else culet center is maximum height point

StepCuts / Triangle

• Girdle center - center of maximum inscribed center (MIC)
• Table center - table centre of mass
• Culet center:
  • if culet has facets - culet center is its center of mass
  • else culet center is maximum height point

Unknown cuts

• Girdle center - girdle centre of mass
• Table center - table centre of mass
• Culet center:
  • if there is a big segment includes point near maximum height point and slope less then 5 degree, culet center is the segment center
  • else if culet has facets - culet center is its center of mass
  • else culet center is maximum height point

Comprehensive list of the Helium report parameters:

• Position normalization
• Diameters, Width & Length
• Main diameters
• Ratio (L/W) & Girdle Ratio
• Table
• Culet
• Total height
• Crown height
• Pavilion depth
• Upper and lower girdle facets' heights
• Crown height at girdle minima
• Pavilion depth at girdle minima
• Depth and length girdle facets
• Girdle thickness
• Girdle types for cushion as red, yellow, green and blue
• Corner angle width and Corner angle length
• Facets' slope and azimuth angle
• Facets' slope and azimuth angle for rounded fancies (obsolete)
• Azimuths deviation from ideal
• MIC & Girdle to MIC
• Girdle-Table offset (by table axis),
  Girdle-Culet offset (by table axis),
  Table-Culet offset (by table axis)
• Crown painting and Pavilion painting
• Girdle type (obsolete)
• Trapezium parameters
• Extra Facet / Natural
• Twist
• Statistical values

Measurements are used in different systems and tools:

• Lower girdle facets or halves
• OctoNus spread & AGS spread