Several years ago, the Gemological Institute of America (GIA) created the system to classify polished diamonds and identify their value: the 4 Cs.
The system of the 4 Cs of the GIA is based on one fundamental concept: Rarity. The more a diamond is rare and more has value than another, and the combination of the 4 Cs determines the value.
The 4 Cs are the following and are in order of relative importance:
This is definitely the most important feature of a polished diamond.
It should first make a distinction between the cut and shape. “Cut” is the technical process used to enhance the most of the characteristics of brightness and sparkle of the gem, while “shape” is simply the pattern followed to cut the stone: round, pear, heart, square…The brilliant cut round shape is the most widespread and appreciated. When a diamond has a fine cut, following the ideal proportions and the relative parameters of symmetry between the facets, the light that enters from the top of the stone is refracted inside the diamond from one facet to another and then reflected back through the top of the stone.
There are some degrees to evaluate the Proportions, Polish and Symmetry of a diamond: “Excellent”, “Good”, “Good”, “Poor”, “Fair”, “Unusual” …
To hear someone speaking about the color of a diamond may seem absurd, but it is not. Diamonds exist in all colors from yellow to green, blue to pink, and they are the most suitable for investment, but more available in nature and the most popular on the market are the “colorless” with no defined color and that are also commercially called “white diamonds”. These are classified through the color scale created by the Gemological Institute of America (GIA), while for the natural colored diamonds there is no scale. In the scale of colorless diamonds, what is measured, is the absence of color: higher is the absence of color greater will be the value of the diamond respect to another.
The scale ranges from “D” to “Z”, where “D” is the absolute colorless and “Z” is near to natural fancy yellow.
How to make a diamond unique and recognizable in time?
It’s simple: by identifying its internal characteristics, as if they were its fingerprints because there is no diamond equal to another. These internal features, identified at 10x magnifications, are called “inclusions” and they are made of carbon or other mineral fragments which were enclosed in the diamond during the crystallization process occurred hundreds of thousands of years ago. Their presence and thus their amount, their position, size and color are the identity card of the diamond. The diamonds that do not have internal and external inclusions are extremely rare.
The grading scale of the clarity of the Gemological Institute of America (GIA) identifies 11 grades of clarity at 10x magnification:
The weight of the diamonds as other gemstones is measured in carats (ct).
The name comes from the seed of the carob tree which was used in ancient times as the weight: carat. The metric carat is a unit of measure that the decimal equivalent of 0.2 grams, then 1 gram = 5 carats. Not to be confused with the value of a carat (kt) used in jewelry expressing a relationship that indicates the quality of the alloy used. One carat is divided into cents (0.01-0.02 …) called “points”. But why is it important to evaluate a diamond? Larger diamonds naturally weigh more and are also rarer than the smaller ones, which means they command a higher price. Value is more than proportionally as increasing weight.
So if, for example, a diamond weighing 1 carat costs 100, a diamond that weighs 2 carats will not cost 200 but 240 or more.
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