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5 C's of Diamond
Clarity
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:
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Symbol
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Meaning
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Definition
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F
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Flawless
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Free from all inclusions or blemishes.
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IF
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Internally Flawless
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No inclusions visible at 10x magnification.
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VVS1
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Very Very Slightly Included #1
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Inclusions that are extremely difficult to locate at 10x.
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VVS2
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Very Very Slightly Included #2
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Inclusions that are very difficult to locate at 10x.
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VS1
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Very Slightly
Included #1
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Minor inclusions that are difficult to locate at 10x.
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VS2
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Very Slightly
Included #2
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Minor inclusions that are somewhat difficult to locate at 10x.
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SI1
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Slightly Included #1
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Noticeable inclusions that are easy to locate at 10x.
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Sl2
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Slightly Included #2
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Noticeable inclusion that are very easy to locate at 10x.
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I1
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Included #1
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Obvious inclusions. Somewhat easy to locate with the unaided eye.
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I2
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Included #2
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Obvious inclusions. Easy to locate with the unaided eye.
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I3
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Included #3
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Obvious inclusions. Very easy to locate with the unaided eye.
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Cut
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:
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Table(%) = |
longest table measurement(in mm)
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| average girdle diameter(in mm)
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And for depth percentage:
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Depth(%) = |
depth (in mm)
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| average girdle diameter (in mm)
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Rough diamonds look like beach glass -- pretty, but not particularly amazing.
Cutting techniques that bring out the diamond's brilliance can reduce the final
gem size by half, but can increase its market value four times. Modern cutting
techniques that bring out the best brilliance from a diamond were established
at the beginning of the 20th century. Before, diamonds were frequently cut to
maximize carat weight -- as with the "old mine cut" -- rather than light
diffusion.
Diamond gemstones are created by cutting precise facets , or tiny polished
faces, in the stone. This is possible by cutting along the diamond's natural
points of cleavage, by grinding down its surfaces with another diamond, and by
employing modern laser techniques.There are 58 total facets on the round
brilliant diamond. Thirty-three facets, including the table - the largest top
facet - are cut above the girdle, the diamond's widest circumference. Below the
girdle - in an area called the pavilion -- are twenty-four more facets and the
culet , or bottom point.
Brilliance is the term used to describe those astounding flashes of light you
see when bright light hits a diamond. Brilliance is caused by white light
reflecting off the diamond's surfaces and the mirrored depths of the pavilion.
Flashes of color within the stone are called fire or dispersion . Fire and
brilliance give diamonds their beauty and increase their value.
The key to excellent fire and brilliance is proportion . Light striking a
diamond that is cut too shallow will fall through the bottom rather than
reflect as brilliance. Likewise, a diamond that is cut too deep will have less
brilliance because light hitting the bottom cannot be bounced back to the top.
In the jewelry industry, the word "cut" usually brings to mind the shape
or the outline of a diamond's front. The seven most popular and fashionable
shapes are the round brilliant, marquise, pear, emerald, oval, princess, and
heart.
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Round Brilliant -- The modern classic for cut diamonds. 58
facets offer great brilliance and stability. This shape is most common and most
popular for solitaire pieces.
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Marquise -- Currently a very popular shape for engagement
rings. The brilliant style marquise, with its distinctive pointed oval form,
carries the name of a French noblewoman. The pointed ends make this shape the
most fragile and the most expensive of brilliant style cuts.
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Pear -- Less expensive than the marquise, but just as
distinguished looking. Cut to maximize brilliance like the round brilliant, the
pear shape has one pointed end -- and so, it has the same issue of fragility as
the marquise.
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Oval -- If you are looking for a unique alternative to the
round brilliant, the oval may be just what you want. It has excellent light
dispersal like the round, but its shape may make it look larger than a round
diamond of the same weight and quality.
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Emerald -- So named because it is the shape most associated
with emerald gemstones, this is the most expensive shape for cut diamonds.
Fewer facets distract the eye from any inclusions, so the emerald cut diamond
generally has higher clarity. But, with fewer facets comes less brilliance than
the other shapes. And, the emerald cut can look dull quickly, especially if you
tend to wash your hands and put lotion on while wearing your jewelry.
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Princess -- Remarkably lovely and eye catching, this diamond
shape is very popular right now, especially in "invisible" settings. Better
yet, its sparkle won't dull as quickly as the emerald cut.
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Heart -- A very special and romantic shape. The heart shape
diamond is difficult to make perfectly proportioned, but it's not hard to love.
This shape is full of fire and brilliance like the round and the marquise.
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Baguette -- These small, rectangular diamonds are cut to
maximize brilliance like the shapes described above. But, their major duty is
to fill in channels , or stable grooved tracks, around a gemstone
centerpiece. Jewelry designers sometimes only use baguettes to create dramatic
contemporary looks for rings and pendants.
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Color
Color In recent years, a de-facto international standard grading
system has evolved, based on the standards of the G.I.A., the Gemological
Institute of America. Terminology differs in European standards, but the grades
are identical.
The following table shows the GIA, traditional UK , and CIBJO color scales,
together with our graphical representation. We have assumed that your computers
video card can display at least 256 shades of color. Obviously this chart may
appear different on different monitors; therefore it is advisable to treat our
color column in the table as only a general guide rather than as an exact
rendition of any particular color.
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GIA
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UK Traditional
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CIBJO
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Color
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Our Comments
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D
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Finest White
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Exceptional White +
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Colorless
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E
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Finest White
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Exceptional White
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Virtually Colorless
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F
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Fine White
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Rare White +
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Virtually Colorless
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G
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Fine White
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Rare White
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Virtually Colorless
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H
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White
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White
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Virtually Colorless
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I
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Commercial White
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Slightly Tinted White
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J
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Top Silver Cape
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Slightly Tinted White
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K
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TSC to Silver Cape
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Tinted White
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L
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Silver Cape
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Tinted White
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M
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Light Cape
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Tinted
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N
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Light Cape
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Tinted
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O
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Cape
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Tinted
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P
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Cape
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Tinted
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Q
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Cape
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Tinted
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R
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Cape to Dark Cape
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Tinted
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S-Z
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Dark Cape
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Tinted
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Most people would find it difficult to differentiate between diamonds in the
first four color grades, D, E, F and G, even when un-mounted. Mounted diamonds
of these grades, and also H and I appear colorless. The ability to notice any
color in these grades will vary with the color perception of the individual.
Small mounted diamonds down to J and K color will usually also appear colorless
except under careful inspection, and then only by those with good color
perception. Slight color may be visible in larger stones
Lower color grades will show increasingly noticeable color, although well
proportioned stones may appear lighter viewed from above, when mounted, than
their body color would suggest.
Standard scales do not yet extend to brownish diamonds, or diamonds of other
colors.
What is a Carat?
Historically the carat is supposed to have been derived from the weight of
locust bean or carob bean seeds, from the Greek Keraton. Until earlier this
century, there were at least two different standards for the carat. In 1914,
the carat, or metric carat as it was known, was defined as 1 / 5 th of a gram.
It is not always easy to establish the weight of a mounted diamond, it would
need to be removed from its mount, and then reset, which always involves some
slight risk, not to mention time and expense.
For round diamonds it is fairly easy to estimate their weight by measuring
their diameter and, preferably, their depth. If this is done accurately, the
weight can be estimated within a fine tolerance (about 1 or 2 %). If the depth
cannot be measured, the weight can still be estimated from the diameter, but
with less precision.
For diamonds of other shapes, it is more difficult to estimate the weight, but
specialized diamond gauges such as the Leverage gauge come with a booklet of
conversion tables, and instructions (albeit rather non-mathematical) for
calculating diamond weights.
Diamonds are measured in terms of weight, not size. The heavier the diamond,
the greater the carat weight . The name "carat" is derived from the
carob seed. These seeds are remarkably consistent in weight and size and so
were the favored scale balances in ancient markets. Carat weight should not be
confused with " karat," the term used to describe gold's fineness or
purity.
A gem carat equals 200 milligrams, and there are 142 carats to every ounce. A
carat is composed of one hundred points. Jewelers evaluate a diamond's
carat weight by using an exceptionally sensitive metric scale that measures
weight in points. So, a 1/4 carat diamond is also called a 25 point diamond.
Because large diamonds are extremely rare -- and diamonds over one carat in
size are becoming increasingly so -- every tiny increase in weight can result
in a big increase in market value. Generally speaking, larger the diamond, the
higher the price. Even a large diamond that has so-so color and clarity will
cost more than a smaller but finer diamond, simply because the larger ones are
scarce.
Weight / Diameter Table
The following table gives an approximate guide to the relative diameter size in
millimeters, and weight of modern round brilliant cut diamonds of ideal
proportions.
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Weight
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Diameter
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Carats
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Millimeters
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0.01
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1.3
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0.02
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1.7
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0.03
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2.0
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0.04
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2.3
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0.05
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2.4
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0.10
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3.0
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0.15
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3.4
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0.20
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3.8
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0.25
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4.2
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0.30
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4.4
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0.33
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4.5
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0.35
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4.6
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0.40
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4.8
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0.45
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5.0
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0.50
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5.2
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Weight
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Diameter
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Carats
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Millimeters
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0.55
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5.4
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0.60
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5.5
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0.65
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5.7
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0.70
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5.8
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0.75
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5.9
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0.80
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6.1
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0.85
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6.2
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0.90
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6.3
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0.95
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6.4
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1.00
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6.5
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1.25
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7.0
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1.50
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7.5
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1.75
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7.9
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2.00
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8.2
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2.50
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8.9
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Weight
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Diameter
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Carats
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Millimeters
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3.00
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9.4
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3.50
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9.9
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4.00
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10.4
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5.00
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11.2
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6.00
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11.9
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7.00
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12.2
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8.00
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12.5
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9.00
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13.1
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10.00
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13.6
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15.00
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16.1
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20.00
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17.7
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30.00
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20.3
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40.00
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22.3
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50.00
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24.1
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100.00
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30.3
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