As noble as this material is, not all diamonds are equal. To define their qualities and values, gemologists have developed the “4C” factors based on the English terms Carat (weight), Clarity (purity), Color (color) and Cut (size). The quality of the diamond will be assessed according to all of these parameters and its value will depend on its quality. The 4Cs are therefore very important if you want to acquire a diamond or even jewelry such as a diamond ring, an engagement ring or a diamond pendant.


The weight of a diamond is measured in carats (this carat should not be confused with that used for gold alloys). One carat (1ct) corresponds to 1/5 of a gram or 200 milligrams. The carat is divided into 100 points, so a 50 point diamond will weigh half the carat, or 0.50 carat.

The carat weight is one of the most important points in defining the price of a diamond, but it is not the only one. Two diamonds of the same weight will not always have the same value, because the price will also be the value of the other elements which constitute the 4Cs (purity, size or color).
You should also know that the value of a diamond is not proportional to its weight, the larger a diamond, the higher its price per carat will be, because diamonds of several carats are very rare.


The purity of a diamond is a primary element in determining the quality of that gemstone, as virtually all diamonds contain impurities. These impurities are tiny traces of uncrystallized carbons or small crystals inside the diamond. These impurities are similar to the fingerprints that help identify each diamond, because they make them unique.

A diamond's impurities (i.e. its inclusions, internal objects, spots or external marks) are identified during examination under 10x magnification (under a microscope or under a magnifying glass), which allows you to define the purity of a gem.


Color is one of the very important characteristics to determine the quality of a diamond, because a diamond is not necessarily white (or colorless), there are diamonds of all colors, but the rarest and most expensive are the colorless diamonds, with a total absence of any trace of color. Particularly detailed scales have been developed by different organizations, such as the GIA (American Institute of Gemmology), the IGI (International Institute of Gemmology) or the CIBJO (International Jewelers Confederation), to precisely classify all diamonds according to their colors.

These scales start with the letter D (a completely colorless, exceptionally white diamond) to the letter Z (a light yellow or brown diamond).


While the first three criteria of the 4Cs are dictated by nature, size is dictated by the hand of man. The term cut can refer to both the shape of the stone (appearance of the diamond) and the style of cut (or arrangement of facets on the stone).

A well-cut diamond can create spectacular plays of light highlighting three main characteristics:
  • Lights: the dispersion of light through all the colors of the light spectrum
  • Brilliance: the total light reflected by the diamond
  • Sparkle: the flashes of light or reflections produced when the diamond is moved.
To fully understand the size of a diamond, you must start by identifying its shape. There are in fact multiple possible shapes, the most popular being the brilliant cut, round in shape. Other diamond shapes are called “fancy” shapes.
The proportions of a diamond are the relationship between the size of the table, the angles of the crown and the depth of the breech. The variation of these proportions will have an impact on the interaction of the diamond with light.
Finish has two aspects: polish, which is the overall condition of the surface of a diamond facet, and symmetry, which is the accuracy of the shape and positioning of the facets.
These factors, along with the thickness of the girdle, affect the overall quality of the diamond cut.


If a diamond is perfectly cut, light penetrates the heart of the stone from all its facets and reflects upwards, creating a beautiful rainbow of colors. If a diamond is not perfectly cut, light will escape through the base or sides of the stone.

In a diamond cut too deep, some of the light will reflect at the wrong angles off opposing facets and escape to the side, causing the center of the diamond to appear black. In a diamond cut too flat, light will escape through the base and the eye will only perceive a dull reflection
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