One of the first things most people learn about diamonds is that not all diamonds are created equal. In fact, every diamond is unique. Diamonds come in many sizes, shapes, colours, and with various internal characteristics.
Four important factors to describe & classify diamonds: Clarity, Colour, Cut, and Carat Weight.
Few things in nature are absolutely perfect. This is as true of diamonds as anything else. Diamonds have internal features, called inclusions, and surface irregularities, called blemishes. Together, they’re called clarity characteristics. Clarity is the relative absence of inclusions and blemishes.
The relative importance of each factor varies from diamond to diamond. For example, an inclusion off to the side of a stone would have less impact on clarity than the same size inclusion located directly under the table. In this case, the position is probably the determining factor.
The diamond colour evaluation of most gem-quality diamonds is based on the absence of colour. A pure and structurally perfect diamond has no hue, like a drop of pure water, and consequently, a higher value. D-Z diamond colour grading system measures the degree of colourlessness by comparing a stone under controlled lighting and precise viewing conditions.