Diamond is the most famous gemstone, and one of the most storied. With a hardness of 10 on the Mohs scale, only a diamond can scratch another diamond - thus it is said to be eternal. It is the most widely used stone in jewelry, and one of the most prized. While diamonds are found in many countries, not all are of equal quality. Diamonds are classified according to the famous 4Cs, which will significantly determine their market value. So let's take a look at what is behind an FVS or HSI diamond.
The 4Cs are: color, clarity, cut and carat. These are the four dimensions that are evaluated in a diamond.
Let's start with color. Color is commonly graded on a scale defined by the GIA (Gemmological Institute of America) from D to Z. A D color diamond is absolutely white, while a Z color diamond is tinged with yellow. The color of a diamond is evaluated in comparison to other diamonds that define the grading scale. When a diamond is more yellow than another Z-rated diamond, it is classified as a "fancy diamond" or colored diamond.
Échantillon de l’échelle de notation de la couleur des diamants incolores utilisée par le GIA.
Colored diamonds are graded differently, based on three characteristics: the hue of the color, its intensity (is the color bright or dark) and its saturation. The scale used ranges from faint (very light color) to fancy deep (extremely deep color, quite dark). The most sought after hue is between these two extremes: it is the fancy vivid (pink, blue, yellow ...). It is often considered the most beautiful color possible for a diamond.
Le Pink Legacy, diamant rose noté Fancy Vivid Pink vendu chez Christie’s.
The second C is the clarity, that is to say the evaluation of the internal characteristics of the diamond. Here we look at the possible presence of inclusions that can affect the appearance of the diamond, detectable using a magnifying glass x10. The grading scale is as follows: IF (internally flawless or loupe clean - no inclusions visible with a magnifying glass), VVS (very very slightly included - inclusions very difficult to see with a magnifying glass), VS (very slightly included - inclusions difficult to see with a magnifying glass), SI (slightly included - inclusions visible with a magnifying glass or even with the naked eye), I (included - inclusions visible with the naked eye).
Now comes the cutting, the faceting done by the hand of man. The proportions of the diamond, its polishing and its symmetry are inspected here. These are the external characteristics of the diamond and its appearance that are studied: are the proportions harmonious, are the different facets well symmetrical, is the polishing uniform, is there any visible damage to the surface... so many questions that the expert who grades the diamond must answer. The proportions are evaluated very strictly for round brilliant-cut diamonds, in relation to so-called ideal proportions, calculated mathematically, and which define the brilliant cut. For other diamond cuts, the notation is a bit more flexible.
Les facettes d’un diamant rond taille brillant.
The last C is the simplest, but perhaps the most fundamental in defining the market value of a diamond: its carat weight. One carat represents a weight of 0.2 grams.
Thus, an FVS diamond is a diamond of F color and VS clarity, while an HSI diamond has an H color and SI clarity. At Alchimie Paris, we only use natural diamonds with a minimum FVS quality.
Because only natural diamonds are systematically graded, synthetic diamonds are only occasionally graded, and imitation diamonds never! To have a diamond appraised, you can ask a gemmological laboratory for a certificate for your diamond on which will appear its grades, thus attesting to its quality.