The traditional '4 C's' determine the value of the diamond. The '4 C's' are clarity, color, cut and carat weight. Cut will be subdivided into the 'finish' and 'proportions'. As far as carat weight is concerned diamonds logarithmically increase in value. This means that a half-carat diamond will have a higher value than two one-quarter carat diamonds.
Likewise, a 1 ct. diamond will have a significantly higher value than two one-half carat diamonds. The reason for this is due to the fact that the larger the diamond is, the harder and rarer it is to find the original crystal from which the diamond is cut.
How to properly view a diamond internally When contemplating purchasing a diamond you should ask the jeweler for a 10X corrected eye loupe in order to properly examine the diamond. A stereoscopic binocular microscope with dark field illumination set at 10X is better still but not essential.
Dark field illumination simply means that the diamond is held against a black background in the microscope and light enters the diamond from the sides and therefore all internal inclusions are easily visible. The circular well within the microscope is lit and the diamond is held at the top of the well. In this manner a great majority of the light enters the sides of the diamond and the clearest internal view of the diamond is obtained. Bring the eye loupe right up to your eye in one hand and hold the diamond ring or the loose diamond in a tweezer in the other hand. At this stage bring the diamond to a distance of approx. one inch away from the eye loupe and focus until the entire interior of the diamond is in clear view.
Try to locate any surface blemishes or internal inclusions within the diamond. You may have difficulty at the beginning so ask your jeweler to help you spot any inclusions present. Be sure that the loupe is 10X since clarity standards and grades are determined under 10X power.
If you view the diamond from the side you will most likely notice a somewhat thick whitish line midway from the girdle to the point of the diamond.
