Introducing the 4 C's
In the 1940s and '50s, GIA developed the 4 C's: the definitive qualities of cut, colour, clarity and carat, as a universal method and reference to compare and evaluate diamonds.
Commonly misunderstood, diamond cut refers far more to than what the shape of a rough diamond is polished into. The cut of a diamond is what determines its brilliance, more simply known as sparkle, and is influenced by the proportions, polish and symmetry of a stone. The GIA employs a five-point scale for grading diamond cut, ranging from Excellent (which has the highest level of sparkle intensity), to Very Good, Good, Fair and Poor (the lowest grade).
Diamond colour is measured based on the degree of colourlessness or lack of colour in a diamond. The highest grade in diamond colour is D being the whitest or most colourless and therefore most desirable. However the difference between two colour grades is sometimes hard to tell in which case a slightly lower colour grade may be more suitable when looking for better value.
Clarity refers to the small imperfections, which occur in a diamond and are often not visible to the naked eye. The size and location of the imperfections play a vital role when determining the price of a diamond. Diamonds with few or no imperfections receive the highest clarity grade. The GIA grades clarity on an 11-point scale, ranging from FL/IF (Flawless) where the diamond is completely free of inclusions to I3 (Included) where the diamond has obvious visible inclusions.
Carat is specifically the measure of a diamond’s weight. Of the 4 C’s, carat weight is the easiest to determine. However how large a diamond appears is also heavily influenced by the shape and cut of a diamond.