cut rating of a polished diamond reflects the capability of the master
craftsman to reveal the fire and sparkle of the rough uncut gemstone.
A diamond's brilliance is maximized through the proper proportions of
depth and width, polish and symmetry of its facets. A diamond with high
color and clarity will look dull if not cut properly. For this reason,
most gemologists agree that the quality of the diamond cut is the most
important of the 4C's.
Before we begin, it is important to understand the structure of a polished
Diameter: The width of the diamond measured from the girdle
Table: The largest horizontal facet of the diamond
Crown: The upper part of the diamond above the girdle
Girdle: The narrow area around the circumference of the diamond
Pavilion: The bottom part of the diamond below the girdle
Culet: The bottom tip of the diamond which may be a point or a facet.
well cut diamond allows light to enter the table facet, travel through
the pavilion where it will be reflected from one side to another, then
reflect back out through the table facet.
poorly cut diamond will allow the light to "leak" out from the
sides or bottom of the pavilion rather than reflect back out the top facet.
Less light reflection equals less brilliance
Polish and Symmetry are two important factors that determine the make
or workmanship of a diamond. The symmetry grade on a diamond report refers
to the alignment of diamond facets. Each round diamond has 58 facets that
must be proportionately sized and aligned. Without proper symmetry, the
light entering a diamond is misdirected as it enters and exits the diamond
resulting in poor dispersion. The polish grade describes the smoothness
and uniformity of smoothness of the diamond facets. A poorly polished
diamond will have polish lines and a rougher texture that creates a duller
polish and symmetry grades are clearly listed in each diamond grading
report. For AGS Laboratories, the grades range from Ideal (ID), Excellent
(EX), Very Good (VG), Good (G), Fair (F) and Poor (P). For GIA Laboratories,
the grades range from EX to Poor.
The finest cut diamonds are those whose proportions follow a formula of
ideal facet alignment, crown angles, and ratio of depth to diameter. This
attention to detail by the diamond cutter toward producing the most ideal
proportions and symmetry of the finished product results in the maximum
brilliance of the diamond.
a diamond cutter begins the process of creating a polished diamond from
a rough gem crystal, he must determine whether or not to sacrifice carat
weight to create a smaller, finer cut diamond, or try to create the largest
diamond possible from the rough, thereby sacrificing quality of the cut.
the Gemological Institute of America (GIA) grades the
proportion and symmetry of a diamond, it will not determine an overall
cut grade. The American Gemological Society Laboratories (AGS) are responsible for an overall cut grade, and have developed a table
that details the specific criteria to grade the cut of a particular diamond.
These cut grades range from 0-10 and are categorized as AGS Ideal (0),
AGS Excellent (1), AGS Very Good (2), AGS Good (3-4), AGS Fair (5-7) and
AGS Poor (8-10).
0 = rarest and most desirable
10 = least desirable
Ideal cut Diamonds are cut to maximize the brilliance of the polished
gem. The precision and craftsmanship is characterized by smaller table
sizes and a distinctly superior dispersion that is easily recognizable
when compared against a non-ideal cut diamond. The diamond cutter usually
sacrifices much of the rough gem crystal to produce a smaller, finer cut
stone with ideal proportions. These diamonds are cut according to specific
AGS Ideal Cut criteria and are the finest diamonds on the market.
Excellent cut diamonds have been afforded the same attention to detail
as the AGS Ideal Cut diamonds, however have a very slight departure from
ideal and are thus priced slightly lower than the AGS Ideal Cut diamonds.
These Excellent Cut grades allow the consumer the choice to purchase an
excellent quality cut at a more affordable price.
Very Good cut diamonds reflect most of the light that enters them
and have a great deal of brilliance and scintillation. The diamond cutter
has preferred to take creative license and create a larger diamond by
straying a bit from the rigid standards of the AGS Ideal Cut. Although
most of the parameters meet the AGS standards, these diamonds will not
meet the AGS Ideal certification requirements.
Good cut diamonds have been cut to create the largest possible carat
weight from the rough diamond crystal. Thus rather than cut a smaller,
premium diamond the cutter has decided to keep the weight and offer as
much brilliance as possible. These diamonds are an excellent value for
customers who want to meet their budget and not sacrifice quality or beauty.
Poor/Fair cut diamonds are not considered to be a good value for the
price. A consumer who purchases an otherwise good quality diamond with
a Poor/Fair cut grading may feel he or she is getting a "good deal"
however the diamond will have poor light reflection and is not considered
a wise investment.
Cut to Buy
superior brilliance and value, select a diamond with a cut grade of
Very Good or Good, and Polish/Symmetry grades of Very Good or Good.
focusing on a higher Cut or Polish/Symmetry grade, you can meet your
budget requirements by selecting diamonds in the near-colorless/SI quality
range. These diamonds provide great overall value for your budget.