Analysis & Grading

GIA Facetware® Help



GIA Facetware Help

The Interface
Parameter Ranges
  Proportion Parameters
  Additional Factors
  Abbreviations
Additional Information on Parameters and Output
  Girdle Thickness
  Girdle Min/Max
  Painting / Digging
  Polish and Symmetry
  Total Depth
Why Facetware Results Differ from GIA Reports
  Crown Height
  Pavilion Depth
  Total Depth


 

The Interface


1) Proportion parameters – required to estimate cut grade. Set to default values when Facetware® opens.
2) Additional factors - limits the maximum possible cut grade. Set to default values when Facetware® opens. For more information about the additional factors, download: Booklet - Finish, Culet, Girdle (high res).
3) Results – displays Facetware output values, including Estimated Cut Grade
4) Reset - returns all parameters to the default values that first display when Facetware® opens.
5) Add Your Parameter Set - creates a temporary list of your input values and corresponding results. Name each parameter set and click “Add” to create the list. List is valid for your current session only.
6) Displays saved parameter sets.
7) Select All – highlights all the sets in your list.
8) Delete – removes selected sets from your list.
9) Email – opens email client to send the selected sets in your list.
10) Print – prints selected sets in your list.
11) Export – converts selected sets in your list to a CSV file.

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Parameter Ranges

 

Proportion Parameters

Parameter Low High Increment
Table Size 44% 72% 1%
Crown Angle 20° 41.5° 0.5°
Pavilion Angle 37.2° 43.8° 0.2°
Star Length 35% 75% 5%
Lower Half 60% 95% 5%
Girdle Thickness 1.5% 11% 0.5%

Additional Factors

Parameter Values
Girdle Min ETN, VTN, THN, MED, STK, THK, VTK, ETK
Girdle Max ETN, VTN, THN, MED, STK, THK, VTK, ETK
Culet Size NON, VSM, SML, MED, SLG, LGE, VLG, ELG
Polish EX, VG, G, F, P
Symmetry EX, VG, G, F, P
Painting/Digging NEG, MOD, SIG, SEV

Abbreviations

Abbreviation Full Name
ELG Extremely Large
ETK Extremely Thick
ETN Extremely Thin
EX Excellent
F Fair
G Good
LGE Large
MED Medium
MOD Moderate
NEG Negligible
NON None
P Poor
SEV Severe
SIG Significant
SLG Slightly Large
SML Small
STK Slightly Thick
THK Thick
THN Thin
VG Very Good
VLG Very Large
VSM Very Small
VTK Very Thick
VTN Very Thin

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Additional Information on Parameters and Output

Girdle Thickness

The range displayed for Girdle Thickness (percentages) varies with the choices for Girdle Min and Girdle Max (verbal descriptions). These three parameters describe different aspects of the round brilliant's scalloped girdle. Girdle Thickness is measured at the eight junctions between the bezel and pavilion main facets, and expressed as a percentage of the average diameter. It describes the distance between the crown and pavilion of the round brilliant. Girdle Min and Girdle Max (verbal descriptions) are assessed in the "valleys" between the upper and lower half facets. Typically the girdle thickness percentage in these valleys is about 1.7% less than the girdle thickness percentage measured at the bezels for normal proportions and when no or negligible painting or digging is present. Characteristics like naturals and cavities can affect the reported descriptions of Girdle Min and Girdle Max (see Booklet - Finish, Culet, Girdle (high res), pages 8 and 9).

Girdle Min/Max

The Girdle Min and Girdle Max values (along with the other additional factors) combine to potentially limit the maximum possible cut grade. Facetware opens with Girdle Min and Girdle Max both set to MED, which causes Girdle Thickness to show a range from 2% to 5%, at 0.5% increments. Changing Girdle Min to ETN changes the Girdle Thickness range to 1.5% - 4.5%. Alternatively, changing Girdle Max to ETK yields a range of 4% - 11% for Girdle Thickness choices. If the desired Girdle Thickness value is not displayed, try changing either Girdle Min or Girdle Max by a few settings to extend the range.

Once the desired value for Girdle Thickness has been chosen, set the values for Girdle Min and Girdle Max, and check that these choices did not force a change to the Girdle Thickness value. For the rare cases where the correct Girdle Min or Girdle Max is not compatible with the desired value of Girdle Thickness, find the estimated grade for the correct proportion combination. Then see page 5 of Booklet - Estimating a Cut Grade, to apply further limitations from the actual Girdle Min or Girdle Max value.

Painting / Digging

The effect of painting or digging out to the cut grade can be applied at four levels: negligible, moderate, significant, or severe. Use this factor to determine whether moderate or stronger painting or digging would limit the estimated cut grade based on the proportions. An explanation and visual presentation of the different forms of painting and digging can be found in the PDF: Booklet - Finish, Culet, Girdle (high res).

Polish and Symmetry

Polish and Symmetry are graded according to descriptions that can be found in the PDF: Booklet - Finish, Culet, Girdle (high res).

Total Depth

The total depth percentage displayed in the output is calculated from the combination of rounded proportion parameters. This calculated value may differ from the reported total depth percentage, which is based on the measured diameter and depth of the diamond.

The calculation of total depth percentage includes the chosen culet size. The default culet size is VSM, and total depth limits (as described on page 5 of the pdf Booklet - Estimating a Cut Grade) are applied to calculated total depth with this default size. Culets of MED and larger limit the initial cut grade based on the proportions.

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Why Facetware Results Differ from GIA Reports

Facetware® has access to the six rounded proportion parameters selected by the user. When the Laboratory grades a round brilliant diamond, 137 individual measurement values are gathered and processed. In some cases, these distinctions lead to rather different values for crown height percentage, pavilion depth percentage, and/or total depth percentage, as described below.

Crown Height Percent

The crown height percentage displayed in Facetware® may differ from the value printed on the report. For GIA Diamond Grading and Diamond Dossier® Reports, crown height is measured at the eight bezel facets. These eight measurements are then averaged and converted to a percentage of the average diameter. The resulting number is rounded to the nearest 0.5%. Facetware® calculates crown height according to this formula, using rounded table percentage and rounded crown angle: Crown Height % = 0.5 (100 - Table %) x TAN (Crown Angle Average). The resulting number is rounded to one decimal place.

Pavilion Depth Percent

The pavilion depth percentage displayed in Facetware® may differ from the value printed on the report. For GIA Diamond Grading and Diamond Dossier® Reports, pavilion depth is measured at the eight pavilion main facets. These eight measurements are averaged, converted to a percentage of the average diameter, and rounded to the nearest 0.5%. Facetware uses culet size and rounded pavilion angle to calculate pavilion depth according to this formula: Pavilion Depth % = 0.5 (100 – Culet Size %) x TAN (Pavilion Angle Average). The resulting number is rounded to one decimal place.

Total Depth Percent

The total depth percentage displayed in Facetware® may differ from the value printed on the report:

The total depth percentage displayed in the output is calculated from the combination of rounded proportion parameters. This calculated value may differ from the reported total depth percentage, which is based on the measured diameter and depth of the diamond.

The calculation of total depth percentage includes the chosen culet size. For girdle thickness choices between 2.5 and 7.0%, a default value of 0.5% (VSM) should be used for comparing this calculation to the total depth percentage limits as shown at  Booklet - Estimating a Cut Grade. Then the actual culet size can be entered to observe any additional limitations to the estimated cut grade.

The Facetware cut grade estimator does not include limitations based on the total depth percentage for girdle thickness choices outside this range (less than 2.5 or larger than 7.0). Further, the GIA laboratory uses the measured unrounded proportions to calculate total depth percentage and apply these limitations, but only rounded proportions are available here. This calculated total percentage may differ from the measured reported value by 0.1 or 0.2. Please use the Feedback form if you would like assistance applying total depth limits for a particular example.

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GIA Facetware

Use Facetware to access GIA's database of more than 38.5 million proportion sets and estimate
a cut grade.

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Free Facetware App

Visit www.gia.edu/facetware-mobile with your iPhone or Android phone.

Cut Grading System Charts & Booklets

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