Properties included in Diamond Reports:
IGI uses the terminology "Diamond Identification Report" although it is
recognized as a certificate . Every lab has a certificate (or "report") number,
which identifies a diamond uniquely. The Lab keeps an internal copy of
everything shown on the certificate, and also additional information. The
certificates can thus be re-issued when they are lost.
Shape and Cut:
Shapes can be categorized as Round, Pear, Heart, Oval, etc...Cutting Styles can
be categorized as Brilliant, Marquise, Emerald, Princess, Step and Mixed.
: Measurements of the Diamond's diameter are calculated to
the hundredth of a millimeter by a non-contact measuring device or a micrometer
which is defined as " minimum - maximum x depth
Diamonds are weighed to the thousandth of a carat with a digital measuring
device. On the Report, the weight is rounded off to the hundredth of a carat.
The proportions of the diamond can be the summed up as its depth, and its table
.Both are expressed as percentage figures. Depth percent refers to the
of the Diamond, measured from the table to
the culet, relative to the width of the stone.
The Table of a Diamond
refers to its largest facet, which is the
main part of the Diamond you look at when the stone is face-up. Table
percent refers to the table size expressed as a percentage of the Diamond's
average width. These ratios determine how well a diamond has been cut.
The Girdle of a Diamond is the border between the crown, or uppermost part of
the stone and the pavilion, and bottom part of the stone. Girdle thickness is
usually expressed as a range since it can vary from thin in one part to thick
in another part of the diamond. The girdle can also be faceted. A faceted
girdle usually enhances the look of the stone, and includes polished facets
into the girdle. Below are example Girdle Thicknesses.
The Culet of a Diamond is the facet on the pointed lower part of the Diamond.
Its existence helps prevent chipping. Some diamonds don't have a Culet.
Finish , Polish &
Finish expresses the polish of a Diamond and the symmetrical
and evenness, in the placement of the facets. Polish
the quality of the polish given on the facets. An excellent polish shows the
care and precision of the Diamond cutter. Symmetry
how precisely the facets are aligned to each other.
Clarity ranges from the best grade of IF, down through VVS1
Clarity expresses the number, size, placement and nature of inclusions and/or
surface irregularities on the Diamond. The experienced Diamond Grader at IGI
examines the Diamond with the aid of an IGI-Microscope, which aids in
identifying the nature of inclusions, and finding pinpoints (very, very tiny
crystals inside the Diamond). The actual grade is decided only on what is
visible under a 10X magnifier.
Color ranges from the best grade of D, down to Z. After Z we approach the Fancy
Color diamonds. Color grades are determined by comparing the diamond with a set
of excellent grade stones under special lighting.
Fluorescence refers to a diamonds reaction when exposed to long wave
ultraviolet radiations. Too much fluorescence can make a Diamond less
A Plot is a graphical representation of the imperfections present in the
Diamond. Every diamond has unique characteristics like fingerprints. By
plotting its characteristics, and combining this with the physical measurements
of a Diamond, a Lab can uniquely identify each stone. This plot is a guideline
for the Grader in the event that a customer returns to the Lab and requests
verification on his diamond purchase. Internal characteristics are plotted in
red, and external characteristics are plotted in green.
Comments are used to describe characteristics which are not discussed elsewhere
on the certificate, or to mention the items not plotted or shown. For example,
"insignificant external details are not shown" is one of the common comments.
All the keywords in the certificate details such as clarity, cut, color,
measurement, size etc can be searched at our bulletin