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Grading Standards
evaluate three of the four value factors--cut, color and
clarity--on its own 0-10 scale. The scales begin at 0 (zero),
the highest grade, and go down to 10, the lowest. The three
factors are expressed separately along with the fourth factor,
the carat weight of the stone, for the final Grade.
Cut
One of the most important factors in determining quality
in diamonds is the cut. Cut is the only value factor
that is a result of human skill. A diamond's beauty must
be balanced against the inevitable loss of weight necessitated
by the very process of cutting. Along with the diamond's
size and shape, the minute details of workmanship play
an important role in the overall beauty and sparkle of
the diamond.
It is important to remember that cut is the most critical
of all the variables effecting the value of a diamond,
more critical even than the carat weight. It is thus essential
that you be well advised of the quality of the cut when
purchasing a diamond.
Color
A truly colorless diamond is extremely rare; most diamonds
possess various degrees of yellow or brown. Small, subtle
differences in color can make a substantial difference
in value. Although increasing shades of yellow reduce
the value of a diamond, they do not necessarily reduce
its beauty. If a diamond is well cut, refraction and
dispersion will often disguise certain degrees of coloration.
Unless a diamond is a fancy color, the Color Grading System
places it on a 0 to 10 scale, 0 being colorless.
To accurately and consistently color grade, a trained
gemologist must utilize special lighting to compare the
diamond being graded to a set of Master Diamonds, which
have met exacting standards of cut, color and carat weight.
The diamond is viewed face-down and reassessed face-up
for the most accurate, consistent grade.
Clarity
Clarity is the evaluation of a diamond's internal and external
characteristics. Inclusions are internal, that is, inside
the diamond. Blemishes are usually very small and are
only on the surface of the diamond.
Two of the most common inclusions are crystals and feathers.
Crystals are merely minerals trapped inside the diamond.
Feathers are breaks in the diamond.
One must use a binocular microscope that magnifies the
diamond ten times to locate these tiny characteristics.
Then, evaluating the size, location, number and color of
all inclusions and blemishes, a clarity grade from 0-10
is assigned. 0 represents a diamond that is Flawless. Every
diamond is plotted for clarity from the top (crown) and
bottom (pavillion) views, with the table size (large top
facet) printed on each grading document in its actual percentage
dimension.
Carat Weight
The fourth and final C is carat weight, the standard usually
used to measure diamonds. A carat equals 1/5 of a gram
(or 1/142 of an ounce), each carat is further divided
into points, each point representing 1/100th of a carat.
In the final analysis, weight may be the least important
of the four C's in determining value. Indeed, comparing
the value of stones by weight is not unlike comparing
the value of paintings by size. After all, a "sofa-size" painting
by an unskilled artist may weigh more than a miniature
by Rembrandt but we assure you that it will not be worth
more.
Weight may be the easiest of the four C's to gauge accurately.
All that is required is a delicately balanced scale capable
of weighting extremely small weights. Yet despite the ease
of measurement and the relative unimportance of diamond
weight, there are some facts you should understand about
weight and price.
For one, as diamonds increase in size, their cost tends
to increase geometrically rather than arithmetically. Thus,
a one carat diamond can cost four or five times as much
as a one-half carat stone of equal quality. For another,
as implied previously, weight does not always enhance the
value of a diamond. In fact, when a stone is improperly
cut, added weight may serve only to reduce its brilliance.
For these reasons you should consult with a skilled gemologist
regarding the question of carat weight, especially as it
relates to the quality of the diamond's cut.
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