AGS Diamond Cut GuidelinesPrevious | Next
History of the Ideal Cut: The earliest guidelines for diamond fashioning
were based more on aesthetics than science, but in 1900 the round brilliant had
evolved into something very close to its current form. No formal work on the
relationships between optics and diamond cutting appeared until the twentieth
century. Then much later, in 1919, Marcel Tolkowsky -- a member of a
Belgian cutting family -- published a short paper entitled Diamond Design. This
was the first analysis of diamond cutting based on modern science theories of
light behavior.
Although
Diamond Design was first published in England, Tolkowsky’s design is often
called the “American Ideal Cut” because US cutters were the first to
produce it in significant quantities. In the e 1950’s, AGS adopted Tolkowsky’s
model as its standard for grading cut. The only modifications to the basic
design were establishing limited ranges for table size, crown height, pavilion
depth and girdle thickness. In 1955, the updated model was renamed the
AGS Ideal Cut.
The demand for AGS Ideal has increased substantially and today numerous cutters
around the world are producing designs loosely referred to as “Ideal Cuts.” The
standards for these “ideals” vary significantly, and as a result, the ability to
recognize and evaluate diamond cutting variations is even more important than it
was a decade ago. The popularity of “ideal cuts” and the increased consumer
demand for verification of this quality factor were among the primary reasons
for establishing the AGS Laboratory . Opened in 1995, the lab has grown
quickly because it is the only US facility that addresses cut grading in diamond
in Diamond Quality Documents. (GIA Gem Trade Laboratory), the primary
industry source for diamond quality documentation does not address the issue of
cut grade in its reports.
American Gem Society (AGS)
The American Gem Society (AGS) Diamond Grading Laboratory uses a cut grade
system that assigns diamonds a cut grade as a number between 0 and 10. The AGS
Cut Grade reflects the impact of 3 key elements on a diamonds beauty and value
-
proportions
-
symmetry
-
polish
Proportions are the sizes and angles of the diamond’s main parts.
Symmetry is the balance and evenness of its faceting and shape. Polish
refers to the diamond’s surface quality, including the presence or absence of
characteristics such as abrasions, scratches, nicks and polish wheel lines
The AGS Ideal 0 cut grade represents the very best in diamond cutting.
AGS 0 is only assigned to a diamond in which correct proportions, precise
symmetry and fine polish are combined to produce an optimum display of
brilliance, scintillation and dispersion. The impression is a harmonious balance
between the physical dimensions of the diamond and the optical components of its
beauty.
As diamonds fall into grades further from O (ideal), their relationship to
beauty begins to diminish. For example, a diamond with a cut grade of 1 or 2
(very fine cut) are very close to 0 in appearance. A cut grade 5 diamond has
variations that detract significantly from overall appeal. It may appear
somewhat “washed out” or slightly dark through the center. Cut grades 10 are the
worst examples of proportioning, symmetry and polish; so they have little visual
“life.”
There
are five factors to consider in evaluation proportions:
-
Table Size
-
Crown Angle
-
Girdle Thickness
-
Pavilion Depth%
-
Culet Size
Diagram shows AGS cut grade 0 (ideal), AGS grade 1 and 2 (very fine) Highlighted
in Gray
To evaluate a diamond’s proportions, simply measure each factor, one at a time,
and assign it’s appropriate grade using the proportions grade chart shown. The
lowest of the five grades (the highest number) will be the diamonds overall
proportion grade. To receive a grade 0 and diamonds must fit into the perimeters
shown for 0 in all five categories.
We
suggest
selecting a diamond that is cut grade 0 (ideal) or cut grade 1 or 2 (very fine).
If you desire a cut grade 0 (ideal cut), it will usually cost 10 to 15% more
than most diamonds with the same color and clarity grades with cut grades 1 or 2
(very fine) The added cost you pay for a 0 grade (ideal) is a result of the
additional manufacturing time the cutter is forced to expend when finishing a
diamond to exact tolerances and the small supply of 0 grade (ideal) diamonds
that are available. AGS 0 grade (ideal) diamonds in large sizes and high
qualities over 1 1/2 carats in size are difficult to find in the market today.
|