Nearly all diamonds have natural inclusions, these are like birthmarks and most are invisible to the naked eye. The different grades of clarity refer to the number, size and position of inclusions in each diamond. As before, the more perfect the diamond is the more rare it will be. The grading scale is as follows:

These inclusions can be used as proof of the diamonds identity. Grading certificates often include a "plot" of the inclusions in an individual stone.   By checking the certificate against the diamond you can have the security of knowing that you are actually getting the diamond that you are paying for.