Now we are at the "heart" of the matter.
For some serious education on the four "C's" and what your strategy should be to get the best deal possible, click on the topics below.
"Shape" refers to the shape and type of cut. The following diamond shapes are the most common.
"Cut Grade" refers to the level of brilliance, fire and sparkle of the diamond. It is determined by specific variances in cutting proportions which cannot be determined by most jewelers, let alone consumers. A GIA (Gemological Institute of America) certificate will tell you what the cutting parameters are. The cut grade is extremely important as it can affect the value by more than 50%.
Some additional terms regarding diamond shapes:
Facet - any of the flat "sides" of the diamond.
Table - on a brilliant cut stone, the top octagonal facet.
Girdle - the typically frosty white ring at the widest part.
Culet - the bottom point (actually a facet) on a stone.
Pavilion - the portion of the stone below the girdle.
Crown - the portion of the stone above the girdle.
Fire - The quality of the diamond that breaks reflected light into a colorful array.
Brilliance - the quality of the diamond that reflects light without changing it (sometimes called sparkle).
Natural - usually found on the girdle - a small section that was on the side of the raw diamond. lt appears as a slightly rough flat spot on the girdle.
Feather - a jewelers way of saying "crack" - appears as a white feather within the diamond.
Diamonds are weighed in metric carats: one carat is equal to 0.2 grams, about the same weight as a paperclip. (Don’t confuse carat with karat, as in “18K gold,” which refers to gold purity.)
Just as a dollar is divided into 100 pennies, a carat is divided into 100 points. For example, a 50-point diamond weighs 0.50 carats. But two diamonds of equal weight can have very different values depending on the other members of the Four C’s: clarity, color and cut. The majority of diamonds used in fine jewelry weigh one carat or less.
Because even a fraction of a carat can make a considerable difference in cost, precision is crucial. In the diamond industry, weight is often measured to the hundred thousandths of a carat, and rounded to a hundredth of a carat. Diamond weights greater than one carat are expressed in carats and decimals. (For instance, a 1.08 ct. stone would be described as “one point oh eight carats,” or “one oh eight.”)
“Color grade" measures the absence of light yellow, brown or gray body color in a diamond. A simple analogy would be that a "D" would represent a clear glass of water, and you would glide down the color grading scale by adding small drops of yellow dye until the water became yellow enough to be the grade "Z". "D" is the highest color grade while "Z" is the lowest grade.
"Fluorescence" is a glow that occurs when about 50% of all diamonds are subjected to strong ultraviolet light sources such as the sun, "black" lights or certain fluorescent lights. Its effect is usually positive by making a light yellow colored diamond look slightly more colorless, but it can have a negative effect when the fluorescence is strong and it makes the diamond look cloudy.
AGS 0: Flawless or Internally Flawless
Flawless diamonds have no inclusions or blemishes visible under 10x. Internally Flawless diamonds have no inclusions visible under 10x, but can have very minor blemishes (marks and features confined to the surface only).
AGS 1 or 2: VVS
A diamond with a clarity grade of 1 or 2 (VVS1 or VVS2) has minute inclusions that are difficult for a skilled grader to see under 10x magnification.
AGS 3 or 4: VS
Very Slightly Included diamonds with a clarity grade of 3 or 4 (VS1 or VS2) have minor inclusions.
AGS 5, 6, or 7: SI
Slightly Included diamonds with a clarity grade of 5, 6, or 7 (SI1 or SI2) have noticeable inclusions that are fairly easy to see under 10x magnification. Sometimes, these inclusions can be visible to the unaided eye.
AGS (7, 8, 9, or 10): I
Included diamonds with a clarity grade of 7, 8, 9, or 10 (I1, I2, or I3), have inclusions that are obvious at 10x magnification. Sometimes, they can be seen with the naked eye. At the lower clarities, may have an effect on the diamond’s durability.