The clarity scale for diamonds is defined as follows:

IF internally flawless No inclusions visible under 10x magnification
VVS1/VVS2 very very slightly included Minute inclusions, extremely difficult to detect under 10x magnification
VS1/VS2 very slightly included Very small inclusions, difficult to detect under 10x magnification
SI1/SI2/SI3 slightly included Small inclusions, easily visible under 10x magnification
P1/P2/P3 piqué Inclusions visible to the naked eye

 

www.onesolitaire.com