Diamond Grading:
The 4 C's
The
4 C's, when referring to diamond value, are color, clarity, carat weight
and cut. All four factors are equally important
in determining the final cost of a diamond.
The criteria for diamond grading, most respected
internationally, was developed by the Gemological
Institute of America (the G.I.A.). The terminology
and systems described on this page, are
those of the G.I.A.
Following,
is an explanation of these terms.
Color
The
color of a diamond refers to the relative
amount of yellow, brown or gray body
color that a stone possesses. The G.I.A.
scale starts at "D" and goes
through "Z", with "D"
being void of any body color, and "Z"
having a light yellow, brown or gray
color.
With
actual stones, the color difference would
appear like this:
Clarity
Practically
all diamonds contain naturally occurring
internal characteristics called inclusions.
The size, nature, location and amount
of inclusions determine a stone's clarity
grade and affect its cost. Clarity is
determined using 10X magnification.
By definition, if something is not visible
at 10X, it does not effect the clarity.
Flawless |
VVS1 |
VVS2 |
VS1 |
VS2 |
SI1 |
SI2 |
I1 |
I2 |
I3 |
Flawless/Internally Flawless= No inclusions
visible, by an expert at 10X magnification |
VVS1-VVS2= Very, Very slight inclusions
very difficult for an expert to find
under 10X |
VS1-VS2= Very slight inclusions difficult
for an expert to find under 10X |
SI1-SI2= Noticeable, relatively easy
to find under 10X. Not visible w/o magnification
in a face-up direction. |
I1-I3= Obvious under 10X, may be visible
to the unaided eye, I3's inclusions
may effect the stone's durability. |
Carat Weight
Carat
is a unit of weight, not size. There
are 5 carats in a gram. The weight of
a diamond is measured in carats. A carat
is divided into 100 parts, called points.
1
carat =1.00 carat=100points |
1/2 carat= 0.50 carat= 50 points |
1/4 carat=0.25 carat= 25 points |
Cut
At
the turn of the last century, it was
mathematically determined, what the
optimal proportions for a diamond should
be to assure maximum brilliance and
dispersion. Those proportions are as
follows:
The
quality of a diamond's cut makes all the difference in how the
stone appears. A poorly cut "D",
Flawless stone, can look dead and lifeless,
whereas an ideally proportioned diamond
of much lower color and clarity will
appear radiant and dazzling. So, why
aren't all diamonds ideally proportioned?
The answer is quite simple. Diamonds
are sold by weight. Stones cut to ideal
proportions waste more of the diamond
crystal, therefore weigh less than stones
that are cut to maximize weight.
Here
are examples:
The
diamond below will weigh more because
of the shallow crown, and exaggerated
table size. Not to mention, that another
diamond of shallow proportions could
be cut from the remaining crystal.
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