While natural diamonds are not formed in sterile environments they can inherently contain impurities that can become visible under magnification. Clarity is described as the amount of and placement of inclusions (internal characteristics) within or blemishes (external characteristics) on the surface of a diamond, as viewed under 10x magnification.
Similarly to the color of a diamond, less is more when referring to the number of imperfections that a diamond contains, where higher values result from an absence of inclusions and blemishes.
Clarity grades are divided into 11 separate categories ranging from;
Flawless (FL), where no blemishes or inclusions are visible to a trained eye under 10x magnification, to Internally Flawless (IF), to Very Very Slightly Included (VVS1 and VVS2), to Very Slightly Included (VS1 and VS2), to Slightly Included (SI1 and SI2), and finally to Included (I1, I2, I3), where inclusions are obvious to the trained eye under 10x magnification and occasionally to the naked eye.