THE 4 C'S OF DIAMOND GRADING

Diamond Shapes …   Round Brilliant   Oval   Marquise   Pear Shape   Heart Shape   Emerald Cut   Princess Cut   Trilliant   Radiant

Cut, Color, Clarity, Carat Weight
 
Diamonds are typically graded according to 4 different determining factors - cut, color, clarity, and carat weight. These factors, when taken as a whole, very accurately describe the diamond and, if performed correctly, provide a standard. If 2 independent jewelers grade the same diamond and both do so accurately, they should arrive at very similar numbers when estimating value.

There are several established guidelines for diamond grading. The most widely accepted standard is the one established by the Gemological Institute of America (GIA). The GIA was formed in 1931 and is a non-profit organization. The GIA does not buy or sell diamonds, but rather, are an educational and research institute. As such, they are able to maintain an unbiased opinion and are not tempted to overgrade a diamond in exchange for profiting from an increased selling price.

Cut (and Shape)
The "cut" of a diamond is not to be confused with the diamond's "shape". While "shape" refers to the obvious general spatial attributes of the diamond, the "cut" includes the minute details of craftsmanship that play a major factor in the brilliance of the diamond. Two different diamonds may have the same general shape, but one may be cut much more closely to the ideal proportions to produce brilliance while the other may not.

A diamond's "cut" is the only factor, when determining value, that is a result of human skill. A diamond's cut affects the value of the diamond even more than the carat weight. If a diamond is cut by a skilled craftsman, it will have increased brilliance and value when compared to one that is cut by someone of lesser skill.

A diamond can have many "shapes" as shown in the table at the right. Among diamond shapes, the Round Brilliant shape accounts for over 75% of all diamonds sold today. Its 58-facet cut is precisely calibrated through a formula to achieve maximum fire and brilliance.

Color
Color in a diamond actually refers to the ABSENCE of color. The less yellow that exists within a diamond, the higher on the alphabetical scale the diamond will be graded. Colorless diamonds are graded D-F, near colorless are graded G-J, faint yellow are K-M, very light are N-R, and light yellow are S-Z as the chart below shows.
 

 
Clarity
According to the GIA, clarity refers to the summation of the number, size, and placement, as well as the nature of inclusions and/or surface irregularities. Flawless stones are diamonds free of inclusions when viewed under 10 power. The chart below shows how diamonds are rated according to the inclusions that exist. The fewer inclusions and surface irregularities that exist within a diamond, the higher the clarity grading will be. Of note are that diamonds that are rated as I1, I2, and I3 have large inclusions that are easily visible to the naked eye while other ratings usually require viewing under a device with a magnification power of at least 10 and are not normally visible to the naked eye.

 
Carat Weight
Diamonds are weighed according to an extremely accurate digital standard. On carat is equal to 100 points, which is equal to 1/5 gram. Carat Weight is the least subjective of the 4 C's, requiring only an accurately calibrated set of digital scales that is capable of measuring very small weights. One very important factor to keep in mind is that, in general, the price of a diamond increases geometrically with an increase in diamond weight, not arithmetically. For example, a diamond that weighs 2 carats may cost 4 or 5 times as much as a diamond of equal quality that weighs 1 carat.