The value and attractiveness of a diamond is measured by its attributes
contained by the four essential diamond features of
Cut | Color
| Clarity and Carat weight. If you have a basic
understanding of these four qualities, you will know enough to make
intelligent choices in the significant process of buying a diamond.
Cut describes the geometric relationship of a diamond's facets,
which in turn supplies its luster and brilliance.
Color in a diamond is indicated by a scale from D to Z that renders
a colorless (D) diamond to be more valuable
and desirable than one with a
higher indication of yellowish coloration.
Clarity is a calculation of the number and type of natural
blemishes found in a diamond.
Carat is a measure of a diamond's weight. It is not a description
of size.
Diamond Grading, or the summary of these qualities, determines a diamond's
price. Of the four, only Cut is subject to human intervention, and perhaps
is the most important, since, all other features being equal, the quality
of a diamond's cut can enhance or moderate a rough diamond's natural
potential.
Cut
If a diamond is poorly cut, no amount of good color and clarity can make
up for it. That's why a diamond's cut and proportions are pre-eminently
significant. It is what makes a rough stone sparkle and shine; what
transforms it into a dazzling gem.
A diamond's facets, or flat planes on the stone, as they have been cut and
polished will realize the amount of light that refracts through the
diamond. Therefore the better the cut, the finer the luminescence.
The following terms apply to parts of a faceted diamond, and will help in
describing an ideal cut versus ones that are either too deep or too
shallow. (Non-faceted stones are called cabochons.)
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Crown
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The top part of the diamond.
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Girdle
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The edge or border of the diamond.
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Pavilion
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The bottom part of the diamond, measured from the girdle to the bottom point.
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Culet
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The lowest point of the diamond. In certain stones, this may be partially open.
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Table
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The flat top of the diamond, and its largest facet. Also called the face.
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Table Spread
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The width of the table facet, often given as a percentage of the total width of the diamond.
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There are several ways that a diamond may appear to be improperly cut:
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If the table is centered but not symmetrical
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When the table is off-center and asymmetrical
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If
the crown is too shallow (extremely thin)
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When the crown is too heavy (extremely thick)
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If the pavilion is too shallow
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When the pavilion is too deep
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Diamond shapes
Color
A diamond is deemed colorless for its capacity to absorb all light rays
equally. These are identified as in the D to F range, and they have no
detectable color, allowing the maximum amount of light to shine through
the diamond. They are the most expensive.
Diamonds in the G to I range may appear to be colorless to the naked eye,
but they exhibit a minuscule amount of yellow and are called Near
Colorless. These may be more affordable and may appear to be just as
brilliant as a colorless diamond.
J to M stones will exhibit Faint Yellow traces.
Diamonds rated from N to Z in the color scale will show deeper yellowing,
and even tinges of brown and gray.
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GIA
Diamond Color Scale :
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Fluorescence
That bluish sheen which can be observed in a diamond under ultra-violet
lighting, is known as fluorescence: a quality that subtly conveys on a
diamond its mysterious allure.
It is not well known that medium to strong blue fluorescence in a quality
diamond will actually improve its brilliance and loveliness.
Yet
uninformed buyers are typically troubled by the mere mention of
fluorescence in a stone.
The fact is that fewer than 10% of gem quality diamonds will exhibit this
blue fluorescence either in an incandescent lighting situation or even
when viewed in sunlight, which has strong ultraviolet properties.
There is no need to fret over fluorescence. In D - H color stones,
fluorescence only rarely will make the diamond look cloudy.
A Faint Yellow
(J - M color) stone with good fluorescence will actually appear is if it
is Near Colorless. So, for the price-conscious consumer, buying a
yellowish diamond with strong fluorescence can actually be a gain.
Blue is the most widespread color of fluorescence. But green, yellow,
pink, white and greenish-blue fluorescence are also found in diamonds.
Clarity
Clarity refers to the presence of internal flaws or inclusions in a diamond. The
type and placement of these imperfections are often as significant as
their presence when determining the value of a diamond. Generally, the
fewer the inclusions, the more valuable the diamond.
These flaws will normally be invisible to the naked eye and require
viewing by a jeweler's magnifying loupe in order for them to be discerned
and appreciated.
Clarity Grading Scale of the Gemological Institute of America:
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FL
- IF
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Flawless
or Internally Flawless. FL diamonds are very rare and exhibit no
inclusions even under 10X magnification.
IF may show minor
blemishes.
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VVS1
- VVS2
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Very,
Very Small Inclusions.
Requires 70X magnification to observe
minute inclusions.
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VS1
- VS2
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Very
Small Inclusions.
Requires 30X magnification to clearly view
inclusions.
These appear as feathers, clouds or small crystals.
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SI1
- SI2 - SI3
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Small
Inclusions. Described as clouds, crystals, knots, cavities and
feathers observed clearly with 10X magnification.
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I1
- I2 - I3
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Imperfect-Eye-Visible
Inclusions
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Crystals are mineral deposits inside the diamond. Clouds are specks that
give a diamond a milky appearance. Feathers are small tiny cracks that
look like feathers. Other common inclusions are called Pinpoints,
Naturals, Scratches, Knots and Cavities.
Inclusions are significant in terms of their effect to block and divert
the flow of light through a diamond. Additionally they provide each
diamond with a unique fingerprint that makes it unique and identifiable,
primarily through certification by Diamond Grading Reports.
Carat
A diamond's weight is expressed in carats, and one carat is roughly
equivalent to 200 milligrams. Each carat has 100 points, and fractions of
a carat can be decimally expressed as equivalent points. For example a
3/4-carat diamond has 75 points.
The complication of decimally expressing fractional carat weight is the
industry norm of giving fractional carat weight a broad decimal range to
maintain its qualification within a particular fractional carat weight.
For example, a 1/2-carat diamond may have between 45 and 58 points and
still be considered a 1/2-carat stone.
Diamond prices may increase disproportionately with the size of a stone
because larger-sized diamonds are more rare.
While it is a primary measure of a diamond's value, carat weight in no way
exceeds the importance of cut, clarity and color in estimating the worth
of a diamond. All 4Cs must be taken into consideration when looking for
the best diamond to meet your budget.
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