Clarity
rings Clarity refers to generally minute imperfections or birthmarks, with which all diamonds form. We grade for clarity though a ten-power microscope, so even those rare diamonds graded as flawless are only flawless at ten-power. If we were to go to higher magnifications we would more likely find imperfections in them as well. To grade clarity we use abbreviations such as FL for flawless; VVS for very, very slight; VS for very slight; and SI for slight imperfections. Diamonds with obvious imperfections are graded as I for imperfect. There are sub-grades to each of these categories as well. Under 10X magnifications a diamond is graded as:

Flawless or Internally Flawless will have no inclusions visible
VVS1 - VVS2 may have minute inclusions, extremely difficult to find
VS1 - VS2 may have minor inclusions, difficult to find
SI1 - SI2 may have noticeable inclusions, easy to find
I1 – I2 may have obvious inclusions, just visible to the naked eye

The important thing to keep in mind regarding clarity is that out of the eleven possible grades, the first eight are going to look the same to the naked eye under normal conditions.