A diamond that is virtually free of interior or exterior inclusions (commonly reffered to as flaws) is of the highest quality, for nothing interferes with the passage of light through the diamond. To determine a diamond's clarity, it is viewed under 10x magnification by a trained gemologist. Small inclusions neither mar its beauty nor endanger its durability.
Flawless: No internal or external flaws.
Internally Flawless: No internal flaws. Very rare and beautiful diamonds which are quite expensive.
VVS1, VVS2: Very, Very Slightly Included: Very difficult to see inclusions under 10x magnification. An excellent quality diamond.
VS1, VS2: Very Slightly Included: Inclusions are nearly impossible to view to the unaided eye for most diamonds. Exceptions to this rule could be when the diamond is viewed from the bottom, or for diamond shapes that are not brilliant cut and have larger facets which makes it more difficult to conceal the diamond's flaws. For the most part VS diamonds are very clean.
SI1, SI2: Slightly Included: Inclusions are visible under 10x magnification, SI clarity diamonds are usually of the best value since inclusions are typically not visible to the naked eye and prices are reasonable when compared to prices of the VS2 qnd up clarity grades.
SI3: Slighty Included-EGL: SI3 is an EGL grade that has also been adapted by other grading labs. It is not recognized by GIA or AGS. For the most part, an SI3 graded diamond is usually comprable to a "good" I1 clarity by GIA. When shopping for an SI3 graded diamond online, it's always a good idea to buy a stone where you've seen a clear picture and the diamond dealer has assured you it's of a good quality.
I1: Included: an I1 clarity diamond will have a visible flaw which can be seen with the naked eye, but there should only be one major flaw which is not too obvious from a little distance. If our budget only allows for an SI3 or I1 clarity diamond, be sure to examine it thouroughly before purchasing and make sure you can not see any inclusions which you may later regret. A good I1 clarity diamond can still look decent however a poor I1 clarity could look terrible.
I2, I3: Included: These diamonds will have inclusions visible to the naked eye, and will have many black spots from the black inclusions and appear cloudy from the white inclusions, feathers and cracks.