To answer the question about the value of a diamond, an expert conducts a thorough examination of the stone. The following succession of procedures is commonly accepted:
The task of an expert is to distinguish natural diamonds from their synthetic counterparts and imitations. Diamond-detector which is based on measuring heat conductivity, can be used for fast identification. (see "Diamond Identification" topic).
Diamond grading.
Diamond grading is stone evaluation by comparing it to other diamonds in certain criteria. The combination of such criteria represents a system of diamond grading. As a rule, expert grade of a stone employs four parameters (4 "C"):
First "C" - carat weight (ct)
The weight of a diamond is accurately determined by weighing it on a balance or, if the stone is mounted, is estimated by using formulas. The diamond weight is measured in carats (1 ct = 0.2 g).
Second "C" - color
Absolutely colorless diamonds are very rare; most of the stones have tints of various color and intensity. The expert task involves an accurate grading of the color and intensity of a diamond in standard light by using colored masterstones.
Third "C" - clarity
At this stage of grading, all internal defects of a stone are detected, and its clarity grade is established.
Fourth "C" - cut
The shape, cut quality, and finish of a stone are characterized at this stage.

From these parameters, a particular diamond is evaluated against the background of other stones, with respect to which it can have a higher or lower price.


Price estimation.
After the expert appraisal of a diamond, its price should be estimated from currently used price lists. A price list used should be consistent with the system of diamond grading.
Market analysis.
Market factors should be taken into account to determine the ultimate price of a diamond. The price can vary depending on whether a diamond is mounted or not and whether it is presented at wholesale or retail level of market. The price is also affected by certificate, type, type of payment, and the competence of a buyer and a seller in market conditions.