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Clarity, Color, Cut, and Carat Weight.
Clarity describes the clearness or purity of a diamond. This is determined by the number, size, nature, and location of the internal (inclusions) and external (blemishes) imperfections.
The clarity scale is broken down into the following grades:
The above clarity grading scheme is in accordance with the GIA (Gemological Institute of America). It is important to note that the GIA Grading system is not static, and has changed slowly over time.
Color describes the amount of color the diamond contains. This can range from colorless to yellow with slight tints of yellow, gray or brown. Colors can also range from intense yellow to brown, blue, green, pink and red. These fancy colors are rare and therefore more valuable.
| GIA | COLOR - COMMERCIAL GRADING |
| D E F |
Colorless (White) |
| G H I J |
Near
Colorless (White) |
| K L M |
Faint Yellow |
| N,O,P,Q,R | Very Light Yellow |
| S,T,U,V, W,X,Y,Z |
Light Yellow |
The color of the stone can be determined by using a GIA (Gemological Institute of America) Certified set of master stones and/or the Colorimeter, a computer which accurately grades the color of a polished diamond.
Cut refers to the proportions, finish, symmetry, and polish of the diamond. These factors determine the fire and brilliance of a diamond. Well cut diamonds sell at a premium and poorly cut diamonds sell at discounted prices. With the advent of technology, the cut of the diamond can be determined through the use of the Dia-Mension system, a computerized system which takes accurate measurements and proportions of a diamond in seconds, in addition to the standard millimeter gauge.
As an example, a round brilliant cut, which has 58 facets, is shown below. Since the quality of the cut is directly responsible for the stone's beauty, the precision with which the facets are arranged is of prime importance. They determine the amount of light reflected to the eye, called brilliance.
The proportions displayed by the stone
are very significant. Two of the key factors in the grading of cut quality -- table percentage and depth
percentage -- are usually expressed on grading reports. Measurement of
three different parameters allows for easy calculation of these percentages by using the
formulas expressed below. For example, for a round brilliant cut
diamond, table percentage is calculated as follows: Table (%) = longest table measurement (in mm) And for depth percentage: Depth (%) =
depth (in mm)
Without attention to quality
cutting, light is lost and not returned to the eye.
"Premium
Cut" "Tolkowsky
Ideal Cut" "Excellent
Ideal Cut" 58.8% - 63.8% 58.0% - 63.8% 59.2% - 62.4% 58.0 - 61.0% 53.0% - 58.0% 52.5% - 58.4% 13.0% - 17.0% 14.2% - 16.2% -------------- 32.7° - 36.3° 33.7° - 35.8° 32.5° - 35.4° 41.7% - 45.0% 42.2% - 43.8% 41.5% - 44.4% Each cut style above represents, in the
opinion of its respective designer, those proportions which best balance the qualities of
brilliance and dispersion ("fire") within a round diamond. Remember, beauty is
in the cutting! Carat is the unit of
weight for the diamond. A carat is further subdivided in 100 points ( 0.01 carat = l
point ). One carat is equal to 0.20 grams. Value per carat increases with carat
size, because larger rough diamonds occur less frequently. In other words, 2
half-carat diamonds taken together will not cost as much as 1 one-carat diamond, as the
one-carat stone is more rare.
average girdle diameter (in mm)
average girdle diameter (in mm)
Proportions Criteria are as shown below:
Total Depth
Table Size
Crown Height
Crown Angle
Pavilion Depth
It is where the cutter truly expresses artistic skill, as the other 3 C's are determined
by nature alone.
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