Brilliance and clarity in a diamond are features of its purity: the purer the diamond the greater its clarity and brilliance. Most diamonds have natural internal characteristics called inclusions and external features called blemishes. These occur in the volcanic rock where the diamond is created. Clarity, therefore, refers to the color, position, brightness, number and size of such inclusions or blemishes. Lighter inclusions in fancy colored diamonds are the cause of significant drop in clarity grade.
The majority of colored diamonds contain inclusions because of the chemical structure and pressure required to create a diamond. Colored diamond connoisseurs will acquire a stone based on the color saturation and consider clarity as a secondary issue. The third most expensive stone ever sold was a 0.95 carat red diamond for $926,000 per carat in 1987. This stone was heavily included but because of its rich strawberry color, it sold for a world record price. A comparable D-flawless diamond would sell for $20,000 per carat. Diamonds with no external or internal faults are called flawless and there are very few of these in the world.
The GIA has established an internationally accepted grading system, according to which Clarity is graded from Flawless to Imperfect as follows: