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There are 13 key factors to consider when evaluating
a diamond:
- Cut
- Measurements
- Carat weight
- Proportions
- Depth percentage
- Table percentage
- Culet
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- Finish
- Polish
- Symmetry
- Clarity grades
- Color grades
- Fluorescence
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However, most individuals
can make a reasonable evaluation of a diamond using
the 4C's. These consider the weight, shape, color, and
clarity of the diamond. The 4C's are:
Carat is a jeweler's term used to describe the size,
based on the weight of a diamond. A single carat is a 0.2 metric
gram. Assuming that every aspect (or rating) of a diamond
was the same except for the carat size, then the larger
the diamond the greater the value. Because of the other
3 C's, a larger diamond may not be the more valuable.
For example, a diamond with a very poor clarity rating
will probably not be worth as much as a diamond with
a nearly perfect clarity. Diamonds are also measured
in points, with one carat being equal to one hundred
points. Normally, the higher the carat weight, the more
you pay per carat. For example, two quarter-carat diamonds
will not cost the same as a single half-carat diamond
of the same quality.
A Clarity rating is used to describe the internal and
surface marks of a diamond. The scale ranges from flawless
(FL) to imperfect (I) when examined with a 10x magnification.
The inclusions in a diamond may be other diamond crystals,
small garnets, enclosed fractures or pockets, or other
crystals which are common in the diamond. Often inclusions
are referred to as flaws, but inclusion is a better
term since no naturally created diamond is perfect.
Diamonds graded in the I2 or I3 range, may threaten
the durability of a diamond. Outside of this range,
inclusions are rarely seen by the naked eye. The grading
scale, as used by the Gemological Institute of America
(GIA) is:
The Color rating is perhaps the most important factor
to consider when evaluating a diamond. The scale ranges
from colorless (D,E,F) to fancy colors (Z). Colorless
diamonds are much more rare than other diamonds and
are therefore more expensive.
The general shape and style of a diamond is referred
to as its Cut. Different cuts affect the optical properties
of a diamond in different ways:
- Brilliance: How "bright" a stone
appears. Essentially the reflections of white light
within the stone
- Dispersion: The "fire" of the stone.
Dispersion is what causes a prism effect in a diamond.
- Scintillation: How a stone "sparkles".
These are the flashes of light from the facets of
a gem when you move the stone.
- Luster: The "shine" of the stone.
How much light is reflected from the stone.
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