When deciphering the value of a diamond, clarity is one of the most vital aspects that is considered. This is used to refer to the inclusions that are present within a diamond; how easy they are to see and where they are located. Almost every diamond has blemishes and inclusions, although many of them are not visible to the naked eye. It goes without saying that the fewer inclusions there are, the more expensive the diamond will be.
There are a number of different factors that are considered to determine a diamond's clarity grading. This includes the number of inclusions and blemishes and their impact on the stone, i.e. their nature, size, where they are placed, and their overall visibility. Gemological labs have different systems in place for grading, but under the Gemological Institute of America (GIA), diamonds are ranked from Internally Flawless (IF) to Included (I3).
There is a process in place called clarity enhancement that is used to try and 'fix' the fractures or imperfections using molten glass. There is a lot of debate regarding whether this procedure is beneficial or not. However, it is worth noting that it cannot be used on all types of diamonds.