Diamond clarity ratings are determined by the amount of inclusions and blemishes and how visible they are. Inclusions are internal flaws that help make each stone unique. They consist of tiny pinpoints‚ markings‚ and clouding that will affect the overall appearance of the diamond. Blemishes are the external or surface flaws. Flawless diamonds containing no inclusions are extremely rare and very expensive. The majority of commercially sold diamonds contains inclusions that are undetectable to the unaided eye. Learn more about a diamond's clarity.