The exact weight of the stone is determined by weighing it on scales or counting formula. The weight of a diamond is expressed in carats (1 carat = 0.2 g).
Basically all diamonds have a color and intensity. Colorless stones are extremely rare and are the most expensive. To determine the intensity and color of the stone and assign a rating, the expert uses reference colors. Color 9-point scale starts with colorless diamonds, followed by a transition with increasing saturation of yellow color. Each color corresponds to a letter of the Latin alphabet. Colors beginning with D (colorless) and ends with the letter Z (yellow). The lower the ratio, the more expensive the stone. Stones with features below Z (brown) are considered fantasy. Assessment of color is the professional expert with standard white lighting, white background and availability standards.
Determining the purityto investigate all internal defects of the stone and also assign it a rating. By purity is considered to be free of defects from the stone. Its characteristics are classified as inclusions (internal defects) or surface defects. The defect is considered internal, even if its release on the surface of the stone, if it cannot be removed by polishing without losing weight. The most valuable diamonds are free of defects. The assessment of the purity of the stone is to the naked eye or with a magnifying glass with 10x magnification. Takes into account only those defects that are visible under this magnification. If they are not visible in the magnifying glass, but found at even higher magnification, they are not considered defects. These rocks are assigned to the highest performance. When assessing the purity of accounted for the amount of defects, their nature, number, location, color of internal characteristics. In some cases, take into account external characteristics.
The final parameter is a characteristic shape of stone (round, oval, etc.) and the quality of cut (the amount deposited of the faces). There is a full cut (57 facets) and the simplified (17 facets). Classic round cut diamonds have 57 facets.
To decipher the characteristics of a diamond as follows:Example: 1 CU 57 – 0,39 – 4/2АРасшифровка designations: 1 CU 57 – one round brilliant with 57 facets
0.39 in – weight of stone
4 – band color
2 – group purity
A – group faceting