The 4 C's

Cut

This refers to the diamond's proportions, symmetry, and polish, which affect how well it interacts with light. A well-cut diamond will have more brilliance, fire, and scintillation, making it sparkle more noticeably.

Clarity

This refers to the presence of inclusions (internal flaws) and blemishes (external imperfections) in a diamond. Diamonds with fewer and smaller inclusions are generally more valuable.

Colour

This refers to the degree to which a diamond is colourless. The less colour a diamond has, the closer it is to the "colourless" range, and the more valuable it is.

Carat

This refers to the diamond's weight. One carat is equal to 0.2 grams. Larger diamonds are generally more rare and therefore more valuable.