The 4 C’s of the diamond

Those who are not really expert can confuse a little between diamond and brilliant . The first is the rough stone ; the second is the stone cut and worked following the criteria of a particular type of cut called " brilliant " which restores the maximum brightness to the stone itself.

The worked diamond is subjected to an accurate gemological analysis, after which it is assigned an exact qualification from which it derives a certain commercial value.

The value of a diamond is defined on the basis of four classification parameters, namely the famous 4 Cs from the initials of the terms in English:

Carat ( Weight )

The weight of diamonds is expressed in carats (1 carat = 0.20 grams). The carat in turn is divided into cents called " points ".

Clarity ( Purity )

Pure diamonds are considered to be those cut diamonds which, observed with a 10 magnification lens , do not show any inclusion.

The crystal lattice of the diamond often presents interruptions that may depend on crystalline inclusions, cavities, cracks, twinning planes, structure lines, cleavages and internal tensions.

In Germany and Italy, the term purity means internal perfection, while in the USA and Scandinavia external characteristics are also taken into consideration.

In Europe and the United States the clarity of a diamond is measured using the following scale ( called GIA ):

IF or LC

(internally flawless or loup clean) = pure to the lens, free from internal characteristics at 10x.

VVS 1 - VVS 2

(very very small) = inclusions extremely difficult to detect with a 10x lens.

VS1 - VS2

(very small) = very slight inclusions difficult to detect with a 10x lens.

SI1 - SI2

(small inclusions) = small inclusions that are easy to detect with a 10x lens.


(I1) (I Piquè) = inclusions visible immediately with a 10x lens and difficult to detect with the naked eye through the crown.


(I2) (II Piquè) = large and numerous inclusions, easily visible to the naked eye through the crown.


(I3) (III Piquè) = large and numerous inclusions, very easily visible to the naked eye through the crown. Significant reduction in the brilliance of the diamond.

Color ( Color )

In the colorless to yellow series, the color degrees are also defined by the reference to the places of origin of the diamonds.

They are in fact the names of the ancient diamond mines or alluvial deposits from which the term " river " was handed down for diamonds coming from rivers and with which they meant stones that generally had a better color than diamonds from chimneys or " pipes " .

Unique definitions of the diamond color were then added to these definitions:


White - Blue


Excelent White




Lighty Tinted White


Dyed White


Slightly Yellowish




Light Yellow



It is necessary to investigate the nature of the coloring substances of the diamond, or rather the cause of the color, about which it is not possible to say anything for sure. It is believed that the various colors are given by the presence of iron, titanium, samarium and chromium atoms but it is not excluded that they are of radioactive origin.

In some natural colored diamonds analyzed in the laboratory by means of high sensitivity spectrographs, the presence of about 14 different elements was found.

On a theoretical level, the color is to be considered a serious defect with a considerable penalization of the value of the stone but, when it is marked and characterizing, it excludes the same from the normal color categories and inserts it in the classification of the so-called " fancy " diamonds , highly sought after and , consequently, of high value.

Cut ( Cut )

The most used cut is the round " brilliant " or Amsterdam: 58 facets , or rather 57 + 1 , considering 1 the smoothing of the tip of the lower cone, called Culet.

This cut is the one that best brings out the phenomena of refraction and reflection of light in the diamond and is therefore the most appreciated and accepted.

The shape and perfection of the cut take on absolute importance in determining the value of a gem. There are precise proportions between the dimensions of the various components ( table, crown, pavilion, belt ) which must be respected to obtain the best result.

The cut classification has four parameters:


excellent cut, without any deviation from the prescribed tolerances.


good, with slight deviations from the prescribed tolerances (less than 5%).


medium, with significant deviations from the prescribed tolerances (less than 10%).


poor, with serious deviations from the prescribed tolerances (greater than 10%).

If a diamond has an ideal cut, light rays from all directions are deflected towards the center of the stone and reflected across the top with a sparkle of light.

If a diamond does not have the ideal cut , the light will " get lost " on the side ( cut too high ) or on the bottom of the stone ( cut too low ).