DIAMOND APPRAISAL PROCESS
The actual appraisal process involves two primary components. The first is to grade the diamond and the second is to assign an appropriate value.
Included in the actual diamond appraisal are:
... a color photograph of the jewelry item
... a detailed description of the diamond
... metal content determination and weight
... gemstone identification including grading, measurements and weight calculation/estimation
... valuation at appropriate market level
The first part, gemology, is taught by GIA (Gemological Institute of America) and is a very scientific process. The ‘G.G.’ after most appraisers signature stands for Graduate Gemologist and is a diploma issued by GIA for expertise in gemology. The GIA teaches a detailed and systematic approach to grading involving a standardized examination environment, microscopic examination, comparison stones for color and a variety of tools for evaluating fluorescence, cutting, and treatments. This grading report is used to judge the overall quality of a gemstone.
THE 4 C'S OF DIAMOND GRADING
Most of the natural diamonds are formed in the earth's mantle at extremely high-pressure and high-temperature conditions. Formed from Carbon, the growth of diamonds occurs over periods from 1 billion to 3.3 billion years, which approximately represents 25% to 75% of the age of the Earth. Diamond also has relatively high optical dispersion (ability to disperse light of different colors) which results in its characteristic luster and its high desirability as a decorative precious gemstone. All diamonds share certain characteristics that allow us to compare and evaluate them. These characteristics are called the 4Cs.
A diamond's weight is expressed in Carats. Each carat is divided into 100 points, which means that a 1 Carat stone equals 100 points. Some dealers will advertise a ring as 1.00 CTW, which means that all of the stones total one carat.
Each diamond has it's own characteristics. Many factors, including inclusions and blemishes, along with their size, colour and position, help us to determine a clarity grade. The difference between an inclusion and a blemish is that an inclusion is positioned within the stone, while a blemish is on the surface.
Colourless diamonds are the most rare. Most diamonds have slight shades of yellow or brown. The GIA (Gemological Institute of America) color grading system uses the letters D through Z.
Cut is the only characteristic of a diamond derived from a human element. Cut is what gives a diamond it's brillance and fire.There are well over 250 different diamond cuts available and most gem-grade diamonds have 57 facets; the way these are done will have a great affect on the results of the diamond appraisal.
... Elisa J. Propst, GG