VS is the abbreviation for Very small inclusions.  VS stones contain minor inclusions ranging from difficult (VS1) to somewhat easy (VS2) for a skilled grader to locate under 10x.  Diamonds that are graded VS in clarity are still very impressive looking diamonds under a microscope.  Of course nothing is visible at all to the human eye.

With these stones, we are still in a clarity grade that is "impressive" under a scope.  For those of you who are going to be "picky" under a microscope, you may not want to consider going lower than a VS2.  Just kidding, you don't have to be that way to appreciate VS clarity diamonds.  For those of you who are a little more practical (financially speaking), we have one more classification to go before the imperfections get large enough to start being visible with the human eye. 

VS1

Here is one example of a VS1.  The primary inclusions are located around the 8:00 position, which you'll see more clearly in the zoom below when you click on the thumbnail.