A diamond grading certificate is a report given by
an independent and professional gemological laboratory. The diamond
is evaluated for its quality, not its value. Every diamond is
unique. The certificate will map out all the diamond's recognizable
and individual characteristics. Each certificate will include the
diamond's color, clarity, carat weight and cut information (see the
4 C's of quality). The grading report also includes a hand-drawn map
of the diamond's inclusions. Since no two diamonds are exactly alike
you can always check that the certificate matches the diamond.
|
|
|
There are dozens of gemological laboratories
handing out certificates but only a few are respected by the diamond
trade. Some well-known laboratories include the European Gemological
Laboratories (EGL) and the Gemological Institute of America known as
GIA To better understand your certificates here are
some commonly used terms
Stone ID: A Unique number representing your
diamond. This number is registered in a global database.
Date: The date the report was issued.
Cut and Shape: Shapes other than the standard
round brilliant are called fancy shapes or fancy cuts. Their names
are based on their shapes. The best known are the heart, marquise,
pear-shaped cut, emerald cut, princess cut, oval, and radiant.
|
|
|
|
Dimensions: The dimensions of the diamond are
stated as "largest diameter - smallest diameter X depth" for round
shapes and "length X width X depth" for other shapes.
Carat Weight: The standard unit of weight used for
gemstones. One carat equals .200 grams (or 200 milligrams). Usually
abbreviated ct.
Graining: Graining and grain lines reflect
irregularities in the crystal structure. Colorless graining usually
does not affect the clarity grade; but white, colored, or reflective
graining does.
Proportions: Proportion refers to the angles and
relative measurements of a polished diamond. More than any other
feature, proportions determine a diamond's optical properties.
Studies have shown that table size, crown angle, and pavilion depth
have a dramatic effect on a diamond's appearance.
|
Depth%: The depth of the diamond divided by the
average diameter for rounds, or the depth divided by the width of
the diamond for other shapes.
Table%: The average size of the table facet
divided by the average diameter of the diamond for round shapes, or
the width of the diamond for other shapes.
Girdle: The girdle is the outside edge of the
outline of the diamond. The certificate indicates the thickness of
the girdle relative to the size of the diamond, and the condition
either polished or faceted.
Culet: The point at the bottom of the diamond. If
the culet is faceted then the certificate indicates the size of the
facet relative to the size of the diamond.
Finish: Finish grades represent the quality of the
diamond's surface condition (polish), and the size, shape and
placement of the facets, including the evenness of the outline
(symmetry).
Polish: Indicates the care taken by the cutter in
shaping and faceting the rough stone into a finished and polished
diamond.
Symmetry: A diamond's symmetry is the arrangement
of the facets and finished angles, created by the diamond cutter.
Excellent symmetry of a well-cut and well-proportioned diamond can
have a great effect on the diamond's brilliance and fire. Grading
reports will often state the diamond's symmetry in terms of
Excellent, Very good, Good, Fair, or Poor.
Cut: The proportions and finish of the diamond.
With the proper proportions, most of the light that enters a diamond
is returned revealing the diamond's brilliance and fire. Any
deviation of these proportions will compromise the beauty of the
stone.
Clarity: Clarity represents the relative absence
of inclusions and blemishes in the diamond. Clarity is graded under
10X magnification from Flawless to Included based on the size,
nature, position and quantity of the diamond's inclusions.
Color: Assesses to an obvious yellow (Z) when
compared to Master Color diamonds.
Pavillion: Depth The distance from the bottom of
the girdle to the culet is the pavilion depth. A pavilion depth that
is too shallow or too deep will allow light to escape from the side
of the stone, or leak out of the bottom. A well-cut diamond will
direct more light through the crown.
Tolkowsky Ideal Cut: In the 1920's a Russian
Mathematician by the name of Marcel Tolkowsky calculated the
proportions of the facets in a round diamond that would bring an
ideal balance between brilliance and dispersion. Any deviation from
these designs will compromise the beauty of the stone.
Fluorescence: When exposed to ultraviolet light, a
diamond may exhibit a more whitish, yellowish or bluish tint, which
may imply that the diamond has a property called fluorescence. The
untrained eye can rarely see the effects of fluorescence. Diamond
grading reports often state whether a diamond has fluorescent
properties. Fluorescence is not considered a grading factor, only a
characteristic of that particular diamond.
Crown Height: The crown is the upper portion or
the top of a diamond.
Diagram: A diagram approximates the shape and
cutting style of the diamond. Symbols on the diagram include the
type, nature, position and approximate size of a clarity
characteristic.
Key to Symbols: Lists the characteristics and
symbols shown on the diagram, if present. Remember, a diamond
grading certificate from a leading gemological laboratory will
insure you get the quality you paid for.
To learn more about
Diamonds & Diamond Jewelry, visit the leading diamond jewelry
store –
http://www.DiamondSafe.com
Dana Halpert
dana@compucall.co.il
Compucall-Web Marketing
Article Source:
http://EzineArticles.com/?expert=Dana_Halpert
