The 4C's of diamond
The carat (ct) is the first criterion of the 4Cs. This term comes from the Carob seed from a tree called "Carob". These seeds were once used as a standard by gem dealers for their regularity of weight (approximately 0.197 gr/seed). 1 carat of diamond weighs 0.20 grams. Diamond dealers also use a second value by assuming that 1 carat = 100 points. This formulation is only used for gems smaller than 1 carat, in other words, less than 100 points. Today, diamonds are weighed on high quality electronic scales that allow buyers to have an exact value down to a thousandth of a carat. The density of the stone is also important in terms of visual impact: the denser a stone is, the heavier it will be. A diamond has a density of 3.52 while a sapphire, for comparison, has a density of 3.95 to 4.03. For two stones of the same weight, the diamond will be visually larger than the sapphire.COLOR (Degrees of white)
The color of a diamond is the second criterion taken into account by the 4C. It is one of the most important aspects of the choice of the stone. It will determine its beauty and value. Diamonds are classified into several categories ranging from D color to Z color. D is the most colorless color and Z is the color that is most yellow. Thus, for white diamonds, the closer the color is to the D color, the whiter the hue and the higher the price. There are also colored diamonds and black diamonds, which are highly prized by collectors. The color of a diamond is measured by placing the stone on the table and looking through the breech in a white paper. This is also the way used by diamond laboratories.
*For information, all diamonds in NALÓ Joaillerie creations do not go below G color. Our jewelry comes with a certificate of guarantee and stones above 0.35ct are certified by GIA, HRD or IGI.
*Color: G (Extra white, used in jewelry stores and in the jewelry, formerly called "Top Wesselton")
*Color: H (White, used in jewelry stores, formerly called "Wesselton")
*Color I (Shaded white, formerly called "Top Crystal").
*Color J (Shaded white, formerly called "Crystal")
*Color K-L (Lightly tinted, formerly called "Top Cape")
*Color M-Z (Tinted, very light yellow, formerly called "light cape, dark cape")
Clarity is the third characteristic evaluated by the 4Cs. Determining the clarity of a diamond requires an experienced eye. For any diamond over 0.30 carat, it is recommended that you request a certificate to guarantee its clarity. To evaluate the purity of a diamond, diamond dealers and laboratories analyze the stone with a magnifying glass x10. The analysis of the diamond is done by the table, i.e. the top of the stone, in order to see it as a whole. The size, position and type of inclusions determine the stone's purity grade. For greater efficiency, diamond dealers also use the microscope, which allows them to sort large batches of stones more quickly. Inclusions in a diamond can be of several types: liquid, gas or solid. They are clearly visible to the naked eye only from grades P1 to P3 (I1 to I3).
Classification of purity :
*For information, all diamonds in NALÓ Joaillerie creations do not go below VS2 purity. (Except on request) Our jewelry is accompanied by a certificate of guarantee and the stones above 0.35ct are certified by GIA, HRD or IGI.
*Purity: FL (Flawless) is the rarest and most expensive purity grade.
*Purity: IF (Internally Flawless)
*Purity: VVS1 (Very Very Small Inclusion 1)
*Purity: VVS2 (Very Very Small Inclusion 2)
*Purity: VS1 (Very Small Inclusion 1)
*Purity: VS2 (Very Small Inclusion 2)
*Purity: SI1 (Small Inclusion 1)
*Purity: SI2 (Small Inclusions 2)
*Purity: SI3 (Slightly Inclusion 3)
*Purity: PI1 (Included 1 - inclusions visible to the naked eye)
*Purity: PI2 (Included 2 - inclusions visible to the naked eye)
*Purity: PI3 (Included 3 - inclusions visible to the naked eye)
The last criterion of the 4C is the size. It is the characteristic that will most influence the beauty of the stone. It will determine the fire, the brilliance and the sparkle. When the stone is rough, the master cutter analyzes it to determine the ideal shape and proportions for good light reflection. To evaluate the cut, the diamond cutter will consider three criteria: polish, symmetry and proportions. The polish is evaluated by observing the surface of the facets, in order to detect any polishing streaks, scratches or chips. Symmetry takes into account the centering of the table, the centering of the culet, the presence of additional facets, the symmetry of the facets and the good meeting of the facets. Finally, the proportions determine the balance between the different elements of the stone (table, crown, rondiste, breech) these elements must respect certain proportions in order to have a balanced stone that will reflect the light well. These proportions are expressed in % of the diamond's diameter and are mentioned in the certificates issued by the expertise laboratories or between professionals on the stock markets.
***Autre critère à prendre en compte Another criterion to take into account is FLUORESCENCE
Some diamonds when they are passed under an ultraviolet light (UV) present a light which emanates from the stone. This is called diamond fluorescence. This phenomenon is the result of a reaction between light and the atoms of diamonds, which is observed by a light emission. It is caused by the presence of nitrogen in the structure of the gem. This light is usually blue but it can also be green, yellow or orange. Knowing the fluorescence of a diamond is important for several things although it is invisible to the naked eye. For diamonds whose color is graded from D to I, a slight or no fluorescence is preferred. Beyond the letter I, fluorescence will make the stone appear whiter than it really is and thus more beautiful.