Each diamond is unique and it’s specific qualities determines it value. The 4 C’s (Colour, Clarity, Cut, Carat Weight) of diamond quality, created by the Gemmological Institute of America (GIA) are now used globally as the universal method for the assessment of diamond quality.
The diamond colour grade is all about the absence of colour. Thus, a diamond which is chemically pure and structurally perfect has no hue and would be of higher value. Diamonds are viewed under controlled lighting and precise viewing conditions to certain master stones with an existing colour value, in order to establish the diamond’s degree of colourlessness. It should be noted that the GIA colour grading system does not consider diamonds with fancy colours, such as diamonds with hues pink, blue and fancy yellow.
Diamonds are formed deep under the earth’s surface when carbon is exposed to extreme pressure and heat. This process results in numerous internal and external characteristics, which make each diamond unique. The internal characteristics or imperfections are referred to as inclusions and the external as blemishes.
Diamond clarity grading determines the number, colour, position, size and reflectivity of these flaws, and the effect of these imperfections under 10 x magnification. Since no diamond can be entirely pure, the closer it comes to perfection, the value increases.
The carat weight of a diamond refers to the weight of the diamond and not its size. Each carat can also be divided into 100 points. Thus if a diamond is 0.25 ct, it would be referred to as 25 pointer. Thus, the price of diamonds increases with an increase in carat weight, since larger diamonds are more rare and higher in demand than smaller diamonds.
The cut grade of a diamond refers to how well the facets of the diamonds interact with light, or what is generally thought of as sparkle. Thus precision is required during the shaping process in order to deliver a diamond with the correct proportions, polish and symmetry for the desired return of light.
A diamond with ideal proportions returns light out of the top of the diamond, while a diamond with a shallow cut transmits light out of the bottom, and a deep cut to the side.
Therefore, two diamonds with an identical carat weight, colour and clarity can differ in value and appearance due to a different cut quality/grade.
The cut quality/grade of a diamond are usually referenced on the diamond’s certificate using the GIA standards. These standards are Excellent, Very Good, Good, Fair and Poor.