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The 4 C's are four variables
that are used to calculate the value of
a diamond --
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:
|
Symbol |
Meaning |
Definition |
|
F |
Flawless |
Free from all inclusions or
blemishes. |
|
IF |
Internally Flawless |
No inclusions visible at 10x
magnification. |
|
VVS1 |
Very Very Slightly Included
#1 |
Inclusions that are
extremely difficult to
locate at 10x. |
|
VVS2 |
Very Very Slightly Included
#2 |
Inclusions that are very
difficult to locate at 10x. |
|
VS1 |
Very Slightly Included #1 |
Minor inclusions that are
difficult to locate at 10x. |
|
VS2 |
Very Slightly Included #2
|
Minor inclusions that are
somewhat difficult to locate
at 10x. |
|
SI1 |
Slightly Included #1 |
Noticeable inclusions that
are easy to locate at 10x. |
|
Sl2 |
Slightly Included #2 |
Noticeable inclusion that
are very easy to locate at
10x. |
|
I1 |
Included #1 |
Obvious inclusions. Somewhat
easy to locate with the
unaided eye. |
|
I2 |
Included #2 |
Obvious inclusions. Easy to
locate with the unaided eye. |
|
I3 |
Included #3 |
Obvious inclusions. Very
easy to locate with the
unaided eye. |
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.
Be aware! Two
methods used to enhance the clarity
grade given to a diamond are laser
drilling and fracture filling. Laser
drilling is the process in which a laser
is used to drill a tiny hole into a
diamond and the black of the
imperfection is then removed. The
second treatment is fracture filling.
This method is not permanent and
therefore not recommended. All clarity
treated diamonds must be disclosed as
such prior to sale. Diamond
Jewelers of South Carolina does not deal
with diamonds that have been clarity
treated in any way.
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
G
H
I |
Colorless
(White) |
J
K
L |
Near Colorless
(White) |
|
M |
Faint Yellow |
|
N,O,P,Q,R |
Very Light Yellow |
S,T,U,V,
W,X,Y,Z |
Light Yellow |
Be aware! It is possible to
influence the color by irradiation
treatment followed by heat treatment.
This method is not recommended for two
reasons. The first is the risk involved
with exposure to irradiated objects. The
second is the risk of color change over
time. All color treated diamonds must be
disclosed as such prior to sale.
Diamond Jewelers of South
Carolina does not deal in diamonds that
have been enhanced in any way.
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)
average
girdle diameter (in mm)
And
for depth percentage:
Depth (%) = depth (in
mm)
average
girdle diameter (in mm)
Without attention to quality
cutting, light is lost and not returned
to the eye.
Proportions Criteria are as
shown below:
|
|
"Premium Cut" |
"Tolkowsky Ideal Cut" |
"Excellent Ideal Cut" |
|
Total Depth |
58.8% - 63.8% |
58.0% - 63.8% |
59.2% - 62.4% |
|
Table Size |
58.0
- 61.0% |
53.0% - 58.0% |
52.5% - 58.4% |
|
Crown Height |
13.0% - 17.0% |
14.2% - 16.2% |
-------------- |
|
Crown Angle |
32.7° - 36.3° |
33.7° - 35.8° |
32.5° - 35.4° |
|
Pavilion Depth |
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.
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. |
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