The 4Cs rule: Cut, Color, Clarity and Carat.
It is used to determine the price of a diamond based on a report: Cut, Color, Clarity and Carat.
These four qualities make the diamond the most famous of all gemstones in jewelry.
The beauty of its brilliance is due to the fact that it possesses a high refractive index of light and a great dispersive power.
C no. 1 - the CUT: the Cut
The degree of beauty of a diamond's dispersion (rainbow effect) depends, in large part, on the cut and polish of the stone.
This diamond grading criterion is the only one resulting from the work of the diamond cutter, and laboratories assign a cut grade according to the table below.
Diamonds are mainly cut in Antwerp (Belgium), Tel Aviv (Israel), and Gujarat (India) by the Jain community.
Because of its extreme hardness, a diamond can only be worked by another diamond, which is why the stone's cut and polish are its most important elements.
C no. 2 - the Color
Diamonds are also graded by color.
The most common color is "white"
(absence of color: meaning the diamond is transparent and colorless).
These colors are graded from D (purest white) to Z (darkest hue).
The color grading system was established by the independent laboratory GIA
(Gemological Institute of America).
Diamonds of other colors, such as blue diamonds, are called Fancy Colored Diamonds and have a different grading system.
C no. 3 the Clarity: the Clarity
Diamonds also contain a wide variety of inclusions that can alter their appearance.
An inclusion or impurity in a diamond is nicknamed a toad (crapaud) in France.
Inclusions are indicated using the following codes.
C no. 4 - the Carat: the weight
Photo credit Bijouterie Rigal
The mass of a diamond is measured in carats, which is equivalent to 0.20 grams.
The value of a diamond is exponential in relation to its mass.
In other words, a two-carat diamond has a higher value than two one-carat diamonds, since it is considered rarer and therefore more expensive.
Gemological laboratories certify the characteristics of diamonds according to the 4Cs classification.
This certification involves taking precise measurements of the diamonds, assigning a cut, polish, and symmetry grade, analyzing fluorescence, and assigning a unique laser-engraved number to the diamond. The people responsible for this work are professional gemologists. There are few global gemological laboratories; the most well-known are:
Gemological Institute of America (GIA) in New York
Hoge Raad voor Diamant (HRD) in Antwerp;
International Gemological Institute (IGI) in Antwerp;
GGTL Laboratories, in Geneva and Liechtenstein;
Fellow of Gemmological Association (FGA) in London;
American Gem Society (AGS) in New York;
Laboratoire Français de Gemmologie (LFG) in Paris.
The diamond dealer (a term initially referring to the diamond cutter), unlike the gemologist, does not study the diamond but trades it.
Depending on their specialty, their business will involve cut stones or rough stones, with some combining both.