Clarity is a measure of the number of the flaws in the diamond as well as how visible they are and their affect on the diamond's overall quality. The characteristics that determine a diamond's clarity can affect its sparkle and brilliance. The flaws that diamonds can often have are often referred to as inclusions. The inclusions of a diamond range from white and black dots on the surface of the stone to small cracks within in the stone and crystalline growth within the diamond. If you are searching for something such as diamond stud earrings where the diamonds will most likely be even more visible than that of a ring, a higher clarity on the diamonds may be wanted to achieve a brighter sparkle.
The GIA has a grading scale regarding diamond clarity, and it goes off specific criteria that are used to differentiate between grades.
FL: Completely flawless.
IF: Internally flawless; only external flaws are present, which can be removed by further polishing the stone.
VVS1-VVS2: Very Very Slight Inclusions. Only an expert can detect flaws with a 10x microscope. By definition, if an expert can see a flaw from the top of the diamond, it is a VVS2. If an expert can only detect flaws when viewing the bottom of the stone it is a VVS1.
VS1-VS2: Very Slight Inclusions. One can see flaws with a 10x microscope, but not easily.
SI1-SI2: Slight Inclusions. Inclusions are easily visible under 10x magnification. These stones are often "eye-clean".
SI3: Slight Inclusions - This grade is only recognized by EGL and is not recognized by the GIA or other gemological institutions and may be graded by GIA as either SI2 or I1. SI3 diamonds never have any black inclusions or cracks visible to the unaided eye, but may have some very minor white inclusions which can be seen.
I1: Inclusions visible. An I1 clarity graded diamond will have a visible flaw which can bee seen with the unaided eye, but most of the time will only have one major flaw which will not be too obvious.
I2-I3: Inclusions high visible. These diamonds will have inclusions visible to the unaided eye and will have many black spots and appear cloudy.
Most of the flaws of a diamond are tiny imperfections that do not affect a diamond's brilliance. If you are on a budget, it might not be worth it to get a higher graded clarity diamond, such as a VS1, rather than an SI2 grade because both are more than likely going to look the same to the unaided eye. You are only going to start seeing the imperfections under 10x magnification. If you are getting some new diamonds in addition to a diamond ring, such as diamond stud earrings, or vice versa, it is important to get the same or very similar clarity on the added diamonds to make sure they will match better and sparkle the same.