The rarity, therefore, the value of a diamond is determined by its 4 fundamental characteristics.
The so-called 4 C.
The 4 C's of Diamonds are the English initials of the 4 characteristics:
1.Carat; 2. Color; 3.Clarity; 4.Cut.
Let's analyze them individually:
Carat weight is the unit of measurement that determines the weight of the diamond (1 carat = 0.20 grams). It originates from the specific weight of the carob seed because in ancient times it was used as a standard unit of mass because, unlike the other seeds, its weight is almost always 0.20 of a gram.
Color, or rather the absence of color.
Let's take as a reference the system used by the GIA (Gemological Institute of America) which measures the color of diamonds using a decreasing scale that goes from D to Z.
The letter D indicates the total absence of color and, not as many think, that the diamond is white. The further down the stairs the more yellow the color will be, significantly lowering the value of the stone. There are some rare cases of diamonds that naturally have colors like pink, blue and orange but are not downgraded, on the contrary ... these are the Fancy Diamonds . It is fundamental, however, that the color is natural and not induced through one of the two possible treatments, exposure to very high temperatures or through exposure to radiation.
Curiosity: the "standard" human eye is able to glimpse the presence of yellow only from the H downwards, unlike an expert eye.
Purity is perhaps one of the most fascinating aspects of gemology applied to diamonds.
There is no instrumentation that can determine it, everything is entrusted to the expert eye of those who analyze them.
The stone is checked by means of a 10 magnification microscope by an expert eye which, based on the type, quantity, size, color and position of the inclusions, will indicate its "degree of purity".
The cut, fundamental that it is well proportioned.
An incorrectly cut stone will emit its light not from the table (the visible point of a diamond placed with the tip down) but also from other points, making it more dull and less bright.
The goal of the cutter is to get the largest and purest diamond possible from the rough.
It is essential to remember that none of the 4 characteristics is more important than the others. Just one of them is bad enough to greatly devalue a stone