A diamond’s clarity is a measure of the presence of natural inclusions or imperfections found in a diamond. These are formed when the diamonds were formed billions of year ago, as a result of carbon exposed to tremendous heat and pressure deep in the Earth. These natural inclusions are unique to each diamond and are thought of as nature’s fingerprint.
Evaluating diamond clarity involves determining the number, size, relief, nature, and position of these characteristics, as well as how these affect the overall appearance of the stone. Many inclusions and blemishes are too tiny to be seen by anyone other than a trained diamond grader. To the naked eye, a VS1 and an SI2 diamond may look the same, but they are different in terms of overall quality.
The closer a diamond is to flawless with no inclusions visible under a jeweller's loupe, the more rare it is and the greater its value. A diamond’s clarity is graded from F (Flawless) – the rarest of the rare – to I (Included).