The four C’s
Using high technological equipment the laboratory assistants appraise each diamond on its four most important characteristics. Those are known as the four C’s, originating from the English terms Carat (weight), Clarity (purity), Color (color) and Cut (the product). Different laboratory assistants examine the color, purity and way to cut each diamond. In most of the cases their appraisals correspond. Is that not the case, then the diamond gets checked for its properties again and the appraisal of the most experienced laboratory assistant will be followed up.
Is it, however, real?
The diamond is checked firstly and especially on its authenticity. That happens with an apparatus that measures warmth conductance. The stone is also shaken in a powder with hardness degree 9.9. When the stone is not scratched it is supposed to be ok (the hardness of a diamond is degree 10). In practice it seldom happens that a stone is offered that not proves to be a real diamond. Smaller stones are not taken into consideration very much. For them the cost of the research (approximately 75 EUR by carat) is too high in proportion to the market value. Heal now and then discovered a treated or synthetic diamond. After the stone has been examined entirely and a certificate has been issued, it can be sealed on request in a plastic container, with a microphoto of the certificate. This way one always receives the correct stone, that is however if it is companioned by the correct certificate.
When a diamond is offered to the reception of the certificate office, it is immediately weighed on a special balance, to on precise to a one hundred thousand part of a gram. The weight is then converted into carat (up to five figures after the comma). On the actual certificate the weight is mentioned in carat to two figures after the comma, as it is the habit in the diamond world. The term carat has been borrowed from the Latin name of the carob tree, the Ceratonia siliqua. The seeds of the fruit of that tree always weigh between 197 and 216 milligram. Already in Antiquity these were used as a weight entity. Just at the beginning of the twentieth century the metric carat was determined internationally on 0.2 gram.
The purity of the stone depends on the size and the number of inclusions that are in the finished diamond. That is done with special microscopes that magnify 25 times by different lab assistants. But it is nevertheless the research with the ordinary magnifying glass that magnify 10 times, which is being considered as a standard. A diamond is pure (flawless) when an expert with this magnifying glass under standardized artificial light cannot distinguish any inclusions. When the laboratory assistant nevertheless finds one or more inclusions, then the stone gets another certificate: of VVS (particularly small inclusions). In the US (very small definite inclusions) by means of SI (small definite inclusions) to P (or piqué, inclusions that can be observed by an expert with the naked eye). The purer the stone, the more is its value.
Ninety per cent of the sly diamonds have a yellowish base color. The exact color is stipulated with the naked eye by means of a range “masterstones”. The stone is placed in open box with white fond laid between the masterstones by the laboratory assistant, who examines the lower part of the diamond, until the resembling color has been found. The colors vary of “exceptional white +” (exceptional blank +), which is considered the best color to “tinted color” (the less interesting hue of color). They also get an alphabetical quote, with d as best color and z as worst. Because this comparative work is very tiring for the eyes, the laboratory assistant maximum can only work on this for 15 minutes at a time. Natural colored diamonds or fancy’s does are not compared to masterstones, but with special color cards. For these stones a separate color certificate is distributed, provided that diamond is “not treated”.
The cut or the product depends on expertise of the setter. With a special computer program and with the magnifying glass the finishing degree and the proportions of diamond are assessed. The stone is complete measured. Is it, however, symmetrical? Do all facets stand correctly with respect to each other? That is very important for the brilliance of the stone. There are certain optimal proportions and it concerns tenths of millimeters, because it is possible there will appear an undesirable visual impact.