Clarity ratings are determined by the amount and visibility of inclusions in a diamond. Inclusions consist of tiny pinpoints, markings, and clouding which affect the overall appearance of the diamond. There are two types of flaws within a natural diamond: inclusions and blemishes. Inclusions refer to the internal flaws of a diamond and blemishes refer to external or surface flaws.
In general, diamonds with fewer inclusions and blemishes will have a better clarity rating. This increases their brilliance and value. Diamonds with clarity grades VVS1 through SI2 have slight inclusions that may be visible to varying degrees under 10 x magnifications, but are generally not visible to the unaided eye. Diamonds with I1 clarity ratings contain inclusions that are easily seen under 10 x magnifications and may be visible to the unaided eye. Diamonds with I2 and I3 clarities have major inclusions that are easily seen without magnification.