|
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.
The Diamond Source USA 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
|
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 |
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.
The Diamond Source USA
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.
Remember, beauty is in the cutting!
It is where the cutter truly expresses artistic skill, as
the other 3 C's are determined by nature alone.
|
