The GIA clarity grading system
| Category | Flawless | Internally Flawless | Very, Very Slightly Included | Very Slightly Included | Slightly Included |
Included |
| Grade | FL | IF | VVS1 VVS2 | VS1 VS2 | SI1 SI2 | I1 I2 I2 |
 |
|
 |
 |
 |
 |
The GIA diamond grading scale is divided into 6 categories and 11 grades. The clarity categories and grades are:
Flawless category (FL) diamonds have no inclusions or blemishes visible under 10x magnification.
Internally Flawless category (IF) diamonds have no inclusions visible under 10x magnification, only small blemishes on the surface of the diamond.
Very, Very Slightly Included category (VVS) diamonds have very minute inclusions that are difficult for a skilled grader to see under 10x magnification. The VVS category is divided into two grades; VVS1 denotes a higher clarity grade than VVS2. Pinpoints and needles set the grade at VVS.
Very Slightly Included category (VS) diamonds have minor inclusions that are difficult for a untrained grader to see when viewed under 10x magnification. The VS category is divided into two grades; VS1 denotes a higher clarity grade than VS2. Typically the inclusions in VS diamonds are invisible without magnification.
Slightly Included category (SI) diamonds have noticeable inclusions that are easy for a trained grader to see when viewed under 10x magnification. But harder to see with by an untrained grader. The SI category is divided into two grades; SI1 denotes a higher clarity grade than SI2. These may or may not be noticeable to the naked eye.
Included category (I) diamonds have obvious inclusions that are clearly visible to a trained grader under 10x magnification. These included diamonds have inclusions that are usually visible without magnification or have inclusions that threaten the durability of the stone. The (I) category is divided into three grades; I1 denotes a higher clarity grade than I2, which in turn is higher than I3. Inclusions in I1 diamonds often are seen by the unaided eye. I2 inclusions are easily seen, while I3 diamonds have large and extremely easy to see inclusions that typically impact the brilliance of the diamond, as well as having inclusions that are often likely to threaten the structure of the diamond.