This is the Unit in which the weight of a Diamond
is determined. Being simple and objective its the most easy to follow part of the 4 C's grading system.
Ancient traders used the seeds of the carob tree as a unit of weight. Such a seed weighs approx. 0.197gr.
In 1907, the carat weight
was adapted to the metric system and now equals to 0.200 gram and Diamonds weighing less than a carat are measured in points or hundredths.
In practice the weight of a diamond is measured with an accurate
balance to a thousandth of a carat and recorded to a hundredth of a carat. On certificates the third decimal is ignored for
all numbers except 9. In this case the weight is rounded up to the nearest hundredth.
Almost all rough Diamonds contain impurities or so called
"inclusions". Traces of non-diamond materials that were trapped in the mineral during the stone's formation by nature in the
upper mantle of the earth, whilst crystallization took place millions of years ago.
Some of these inclusions can be removed during the Diamond
Cutting process, but only rarely does this process produce a Flawless Diamond, as retaining maximum yield is an important
decision making factor.
The judgment of a diamond's clarity is based on the visibility
of its inclusions, determined by five parameters:
The highest clarity grade is “loupe clean”, literally
meaning, “clean when viewed through a loupe”.
A diamond is called loupe-clean if, after examination by an experienced
grader with a 10x-magnification loupe it has been found free of internal characteristics under standardized light conditions.
The following is the clarity rating system used by diamond laboratories:
• I.F.: internally
free from internal blemishes visible under 10x magnification (small external details tolerated);
• V.V.S.1: very
very slightly included:
minute inclusions extremely difficult to locate under 10x magnification;
• V.V.S.2: very
very slightly included:
minute inclusions very difficult to locate under 10x magnification;
• V.S.1: very
very small inclusions rather difficult to locate under 10x magnification;
• V.S.2: very
very small inclusions rather easy to locate under 10x magnification;
• S.I.1: slightly
small inclusions easy to locate under 10x magnification;
• S.I.2: slightly
small inclusions obvious under 10x magnification;
• P.1- I.1: imperfect:
Large and/or numrous inclusions noticable with the naked eye, without effecting the brilliance of the diamond;
• P.2- I.2: imperfect:
Large and/or numrous inclusions visible with the naked eye and decreasing the brilliance slightly;
• P.3- I.3: imperfect:
Large and/or numrous obvious when viewed with the naked eye, not only decreasing the brilliance slightly but
also its durability;
Inclusions are a diamonds unique "fingerprint" and
no two stones have exactly the same inclusions. Even though many inclusions are removed during the various stages of Diamond Cutting (including cleaving,
sawing, bruting, cutting and polishing) pure diamonds remain extremely rare.
The color of a Diamond is determined by comparing it to an approved series
of samples, so called master-stones, under standardized light conditions.
Most laboratories use D 65-lamps in line with the CIE standard (International
Commission on Illumination), which have a color temperature of 6,500 Kelvin and posses the same strength as natural polar
As the color nuances between two adjoining color stones
are practically unnoticeable when viewed through the table, the subtle difference can only be accurately judged by comparing
them through the pavilion side. To determine
the color, a stone is placed between the master-stones on a neutral white background and a grade is given according to an
alphabetic scale ranging from D, the purest white color, to S-Z.
Approximately 90% of gem diamonds have a basically yellowish
color, caused by its natural contents of Nitrogen. These Diamonds are referred to as Type 1 Diamonds, sub-classed according
to Nitrogen content intensity into A and B.
Whilst Type 1A Diamonds show a lesser Nitrogen content, resulting in
white to increasingly yellowish Diamonds, Type 1B Diamonds are relatively Nitrogen rich, causing a more intense Yellow to
Besides white, slightly yellowish and orange, diamonds can
have many different colors. These are Type 2 Diamonds, which are free of Nitrogen and again sub-classed into A and B.
The color of Type 2A Diamonds is affected by cracks and graining,
resulting in brown, pink and red diamonds, whilst Type 2B Diamonds contain other minerals, such as Boromit, which can lead
to gray and blue Diamonds, or Graphite resulting in Black Diamonds.
Also some Type 2 Diamonds that are colorless do exist. Besides
being free of Nitrogen they are also free of other mineral content, as well as cracks and graining. Some connoisseurs are
extremely fond of them and green Diamonds are the only ones that can be found with and without Nitrogen content and are amongst
the rarest and dearest.
Natural Fancy Color Diamonds as the trade calls these colored Diamonds
can be very valuable, depending on color and its intensity
Color treated Diamonds
Diamonds with artificially created colors do exist,
too. These Diamonds have to be indicated in such a manner, that there can be no doubt concerning the origin of the color.
The term used for this indication is treated and in naming an artificial color the words “natural” or “fancy”
cannot be used. As they are a creation of modern science their value is significantly lower than Natural Fancy Color Diamonds.
Detection of such color treated Diamonds is extremely difficult and requires complex examination. Cases are heard of where
Diamonds were “stuck” in the lab for almost two years. We highly recommend to stay away from uncertified Natural
Quite often the cut of a Diamond is confused with its shape. Diamonds are cut into various shapes depending
upon the original form of the uncut Diamond, which is referred to as rough.
|The most common shapes are:
Whilst the other three aspects of
the 4 C`s are dictated by nature, the cut is the one directly influenced by man. The Cut Proportions are designed to maximize
the amount of light reflected through a Diamond in order to obtain their maximum existence. It is in the hands of the Cutter
to create a magnificent Diamond that sparkles noticeably from a distance or to produce a dull Diamond that lacks the very
life and shine it is desired for. This makes the Cut perhaps the most important aspect in the grading and evaluation of a
For centuries Diamonds have been cut to retain a maximum yield of the rough, sacrificing brilliance for
weight, as the value of Diamonds with higher carat weight increases disproportionately due to their scarcity. Frequently meaning
four times the price for double the weight in equal color and clarity!
It was not until 1919 that this attitude towards Diamond Cutting was questioned, when Marcel Tolkowsky,
a member of a Belgian family of Diamond Cutters and an engineer by education, developed as set chart of proportions for Round
|The Tolkowsky Ideal Cut (1919)
These proportions were derived from mathematical calculations that considered both, brilliance
and fire of Diamonds, hence producing Diamonds superior in sparkle/life. They were published in his book Diamond Design the
same year and recommended to the trade. Ever since referred to as “Tolkowsky Ideal round Brilliant”.
Nevertheless a vast majority of Round Brilliant Diamond Manufacturers kept parameters that differ from the ideal
proportions proposed by Tolkowsky to maintain profitability, by avoiding the additional weight loss and increased production
costs through longer working hours.
had a point as Tolkowsky only offered one specific set of proportions and research has since proven that there are many variants
that produce equally brilliant Diamonds.
the last decades this research has resulted in grading charts that have modified the “Ideal Cut Range” and produced
further proportion grading descriptions. These are in descending order “Ideal Cut", “Excellent”, “Very
Good” and “Good”.
should be understood that these proportion grades are for round brilliant cut diamonds only, that no other mainstream laboratory
except I.G.I issues certificates with proportion grades for Fancy shapes and that “Hearts & Arrows” is not
a proportion grade.
the shape, a diamond cut to well proportions is easy to detect, as it has a higher overall brilliance through its better ability
to reflect light. Therefore it can be of considerably higher value than its equivalent in color, clarity and carat weight.