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The most important criteria in selecting a diamond
are the 4Cs — color, clarity, carat, weight and cut.
Each of these factors has an impact on the quality
and price of a diamond. Learning about the 4Cs will
give you a basis from which to evaluate different
diamonds and compare prices. Buying a diamond is a
very personal decision; you decide which of the 4Cs
is most important to you.
Color
Diamonds are classified by the degree of color they
contain. The most valuable — and rarest — diamonds
are completely colorless. While most diamonds may
appear colorless to the naked eye, they often contain
traces of other colors.
A color scale established by the Gemological Institute
of America (GIA) assigns a letter to the degree of colorlessness
found in a diamond. Beginning with D and ending with Z, each descending
letter denotes an increasing amount of light yellow, brown or gray in the dia
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E, F: Only a gemologist can identify the minute traces of color found in
these diamonds. The stones appear colorless.
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G, H, I: Nearly colorless. Diamonds in this category have a slight color,
but it is not noticeable to the untrained eye.
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J, K, L: Faint traces of color are visible when the diamond is looked at face up.
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M – Z: Obvious color is apparent to even the untrained eye in whatever position
the diamond is viewed.
Clarity
Almost all diamonds contain slight impurities. Often invisible to the naked eye,
these natural “birthmarks” fall into two categories — inclusions, which are internal,
and blemishes, which are external. Inclusions can be the result of trace elements or
minerals that were trapped as the stone was formed. These identifying characteristics
are unique to each diamond and may appear as feathers, clouds or crystals. Blemishes
may be visible on the diamond’s surface, such as scratches or chips.
The fewer the impurities, the more valuable the diamond will be. Since most inclusions
are only visible under powerful magnification, higher clarity does not necessarily mean
that the diamond is more beautiful than a stone of a lesser clarity. But it will make a
difference in terms of how the diamond is priced.
The GIA established a grading system to measure the type and size of these imperfections.
- FL, IF: Flawless, Internally Flawless. There are no inclusions — internal flaws — or blemishes
— external flaws.
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VVS1, VVS2: Very, Very Slight Inclusions. It is very difficult to see inclusions under 10x magnification. An excellent quality diamond.
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SI1, SI2: Slight Inclusions. Inclusions are visible under 10x magnification and may not be visible to the naked eye when the stone is in the face-up position. A good diamond value.
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I1, I2, I3: Obvious inclusions, which are visible to the naked eye.
Carat Weight
The carat weight is the standard unit of weight for a diamond. The word carat is derived from
the word for the carob tree, whose tiny seeds were known for their uniformity and consistent
weight. Diamonds were weighed using carob seeds as a measure. In Asia, rice was used to measure
diamonds. A diamond that equaled four grains of rice weighed 1 carat.
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One carat is the equivalent of 0.2 grams
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One carat is also divided into 100 points.
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Points are generally used to describe increments of weight within a carat.
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The weight of a 3/4-carat diamond can be shown as .75 carats or 75 points.
Carat refers to weight and not size. A 1-carat diamond will not be the same size as a 1-carat
sapphire, due to the density of the gemstone material. Weight affects price. While a 1.00 carat
stone weighs twice as much as a .50 carat diamond, the larger stone is actually more than twice
as valuable because it is rarer. In higher-quality diamonds, the price rises as the size increases.
Cut
Cut refers to the arrangement of facets on the stone, which in turn determines the diamond’s
radiance. Often considered the most important of the 4Cs, it is also the only category where
human skill — rather than nature — affects both the beauty and cost of a diamond.
The diamond cutter follows precise mathematical proportions that relate to the height, width
and depth of the crown (top), girdle (widest part) and pavilion (bottom). When a diamond is
cut to proper proportions, light is reflected from one facet to another and then dispersed
through the top of the stone, resulting in a burst of fire and brilliance. Fire refers to the
flashes of color you see when you look at a diamond; brilliance is its sparkle.
Ideal Cut
In 1919, Belgian diamond cutter Marcel Tolkowsky created the mathematical formula for the “ideal”
cut by devising the optimum combination of angles that would maximize the amount of light that
entered and would then be reflected back out. Ideal cut diamonds can be more expensive because
of the skill and time involved in cutt
Cutting Styles
Cutting styles include brilliant cut, step cut or mixed cut.
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Brilliant cut is designed to maximize brilliance. It has 58 facets — 33
on the table (top), 24 on the pavilion (bottom) and the culet (the bottom point).
In this cut, all 58 facets appear to radiate from the center out through the top
of the diamond.
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Step cut resembles stair steps because three concentric rows of facets are arranged
around the table, the pavilion and the culet. The emerald cut is an example of a step
cut diamond.
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Mixed cut combines elements of both the brilliant and the step cuts. For example, the
crown may be cut as a brilliant cut and the pavilion as a step cut.
Cuts range from ideal to poor. A poor cut diamond, for example, may be cut too deep or too
shallow. In a diamond that is cut too deep, light is reflected through the sides and the
center of the diamond may appear dark. A shallow cut diamond allows light to escape from
the bottom and makes the table appear dull. Too shallow a cut gives the appearance of a
black hole, referred to by industry insiders as a “fish eye.”
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