Clarity refers to a diamond’s absence of flaws such as fractures, cracks, mineral deposits, or scratches. Such flaws are often referred to as inclusions. For convenience, the amount of flaw in a diamond has been somewhat standardized by the Gemological Institute of America (GIA) and the American Gem Society (AGS). Each has its own system which is shown below in the table. On a diamond’s certificate it will usually have one of the grades below as a clarity grade.
| Gemological Institute of America | American Gem Society | Explanation |
| FL (flawless) | 0 | No internal or external inclusions can be seen with a 10x microscope to a trained professional. |
| IF | 1 | Internally Flawless. No internal inclusions, however there are some minor irregularities on the surface that can sometimes be removed with a polish. |
| VVS1 | Very Very Slightly Included 1. One tiny inclusion present under a 10x microscope. | |
| VVS2 | 2 | Very Very Slightly Included 2. Two or three tiny inclusions visible under a 10x microscope. |
| VS1 | 3 | Very Slightly Included 1. Very Small inclusions visible with a 10x microscope. |
| VS2 | 4 | Very Slightly Included 2. Very Small internal flaws. |
| SI1 | 5 | Slightly Included 1. Small inclusions visible with a 10x microscope. |
| SI2 | 6 | Slightly Included 2. Small inclusions easily visible with a 10x microscope but not quite yet visible to the naked eye. |
| I1 | 7-8 | Imperfect 1. Inclusions easily seen under a 10x microscope and barely visible to the naked eye. |
| I2 | 9 | Imperfect 2. Many inclusions easily visible to the naked eye. |
| I3 | 10 | Imperfect 3. Many large inclusions very easily visible with the naked eye. |
I highly recommend going to a local dealer and seeing these different grades for yourself. Take time to look through the microscope at several diamonds. This will help you if you decide to go with a dealer who does not use one of the appraisal systems above.
NOTE: The 10x microscope that most dealers have is known as a loupe.