Usually, a diamond certificate contains information on:
Shape and Cutting style
Measurements
Diameter: minimum - maximum x depth (which are calculated to the hundredth of a millimeter by a non-contact measuring device or a micrometer).
Weight
Diamonds are weighed to the thousandth of a carat with a digital measuring device. On the diamond certificate, weight is rounded to the hundredth of a carat.
Proportions
The depth percent is calculated (from table to culet) relative to the width of the stone. Table percent refers to the table size as a percentage of the diamond's average width. These ratios help determine the quality of cut of the diamond.
Girdle
Uniformity of thickness around the stone (that is why it is expressed as a range). The girdle can also be faceted, or not (a faceted girdle usually improves the look of the stone).
Girdle Thickness Degrees
- extremely thin
- very thin
- thin
- medium
- slightly thick
- thick
- very thick
- extremely thick
Culet
The Culet of a Diamond (if there is one) is the facet on the pointy bottom part of the diamond. Usually, its role is to prevent chipping.
A culet may be labeled as:
- none
- very small
- smal
- medium
- slightly large
- large
- very large
- extremely large
Finish
Describes the surface polishing properties and the symmetry of the facets.
Polish Grades
- excellent
- very good
- good
- fair
- poor
Symmetry Grades
- excellent
- very good
- good
- fair
- poor
Clarity
Reflects number, size, placement and nature of inclusions and/or surface irregularities in the structure of a diamond.
Clarity Ranges
- FL — flawless
- IF — internally flawless
- VVS1 — very very slightly included 1
- VVS2 — very very slightly included 2
- VS1 — very slightly included 1
- VS2 — very slightly included 2
- SI1 — slightly included 1
- SI2 — slightly included 2
- I1 — imperfect 1
- I2 — imperfect 2
- I3 — imperfect 3
The grade is based only on what is visible under a 10X Loupe.
Color
The degree of color in the body of colorless diamonds.
Color ranges from the best grade of D to Z. After Z are Fancy Colors.
Color grade is determined by examining the Diamond next to a master set of color comparison stones, under special lighting.
Fluorescence
A Plot
The graphical representation of the imperfections of the Diamond. It contains the particularities of a diamond — what makes a diamond unique like a fingerprint. It helps verifying the authenticity of a certificate presented with the diamond. Internal characteristics are plotted in red, and external characteristics are plotted in green.
Comments
Here are described characteristics not discussed elsewhere on the diamond certificate, or mention items not plotted.
Any owner of a diamond can submit it to a laboratory for grading, benefiting from impartial, reliable, accurate examination and grading.
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