The four C’s provide a standard for evaluation of diamonds, the “King of gemstones”.
Color Diamonds can cover the entire spectrum of colors. The majority ranges from a perceptible yellow or brownish tint, up to the very rare diamonds described as colorless. Colorless diamonds are the most desirable since they allow the most reflection of light.
Cut A round brilliant-cut diamond has 58 facets. When well proportioned, this shape best shows the stone’s brilliance because it allows the most light to be reflected back to the eye of the observer. Stones that appear lifeless or seem dark in the center are probably poorly cut. When the angle relationship between the crown and the pavillion facets are correct, rays of light entering the diamond, are reflected back to the eye of the observer. When the angle proportions are not correct the stone looks dull and lifeless.
Clarity Most diamonds contain minute traces of non-crystallized carbon and internal stress fractures. Called inclusions, most of these are not apparent to the naked eye, but can be seen in loose stones under magnification. Perfect clarity means that no inclusions are discernible when the diamond is examined under a 10x lens. Inclusions greatly affect the beauty and value of a diamond because they absorb the light rather than allowing it to be reflected back through thefront of the stone. How much they reduce the value of the stone depends on their size, number, and position within the stone. An inclusion in the center of a diamond beneath the table is more visible than one near the edge. It also may be mirrored many times by adjoining facets.
Carat Weight The term carat comes from the ancient practice of weighing diamonds against the seeds of the carob tree. The system was eventually standardized, and one carat was fixed at 0.2 grams. One carat is devided into 100 points, so a quarter-carat diamond is 25 points or 0.25 carat. Although carat is a unit of weight, not size, the carat weight of a diamond has come to refer to particular sizes. If properly cut, diamonds of the same weight should be about the same size.
GIA COLOR GRADING SCALE
D E F G H I J K L M N O P Q R S T U V W X Y Z
colorless near faint very light light
colorless yellow yellow yellow
GIA CLARITY GRADING SCALE
FL: No blemishes or inclusions when viewed under
Flawless 10x magnification.
IF: No inclusions and only insignificant surface blemishes under
Internally flawless 10x magnification.
VVS1 and VVS2: Minute inclusions that are difficult to see under 10x
Very very slight inclusion magnification
VS1 and VS2: Minor inclusions ranging from difficult to somewhat
Very slight inclusions easy to see, face up under 10x
SI1 and SI2: Noticeable inclusions that are easy (SI1) to very
Slight inclusions easy (SI2) to see under 10x.
I1,I2, and I3: Obvious inclusions that are usually visible, face up
Imperfect to the naked eye