It is understandable that any natural gem might have things included within it that are not for the better, visually speaking. Since a diamond’s value is mostly visual beauty, it makes sense that these inclusions and blemishes would reduce its overall worth. Naturally formed diamonds, as with most things found in nature, almost never have a flawless level of diamond clarity. To make a diamond, carbon is compressed at incredible amounts of pressure within the earth, so if anything at all gets in with the carbon then it is bound to be in the diamond, as well. This can include bubbles, fractures or matter that is not actual the actual diamond mineral, all of these are considered inclusions. Blemishes, on the other hand, are chips, scratches or pits that are many times the result of the cutting process. Around the girdle is the typical place to find blemishes.

When one wants to understand the level of diamond clarity present within a given stone, there is a chart that is used in the diamond trade which is a key to the grades given out by those who work with these stones. While it appears complex, reading it over once should make things clearer:

I1 through I3
These three grades (I1, I2, I3) are all visible without magnification. The I stands for Included and all three of these grades are stones that are not considered of good quality. One should take care to avoid such diamonds as their clarity is so poor that they do not make for a good purchase. Most people will be able to spot the flaws, as well, and this could cause the owner some embarrassment.

SI1 and SI2
These two grades mean that Slight Inclusions can be easily spotted under magnification set to level 10X.

VS1 and VS2 
Under 10X magnification, it is possible to view the inclusions present within diamonds given either of these grades. VS stands for Very Slight inclusions.

VVS1 and VVS2
It is difficult to find the inclusions featured within a diamond of either of these two grades, even with 10X magnification. VVS stands for Very, Very Slight inclusions.

IF
This is very rare and the abbreviation stands for Internally Flawless. This means the diamond has no internal flaws, but may feature blemishes on its surface.

F
With the F grade, the stone has no inclusions within or without. It is completely flawless and excruciatingly rare, too.

While a perfect F diamond might seem the most desirable, it is important to remember that until the I grades, a diamond has perfect clarity to the naked eye, its inclusions only being visible under a 10X loupe. This means that diamonds of VVS, VS and IF grades are all remarkable and often stunning. The diamond clarity of an S grade diamond is still very high in terms of what it offers to a piece of jewelry because it is what gemologists refer to as “eye clean”, meaning its flaws are not visible without a magnifying lens. 

The most important thing to remember is that unless a person purchases an I grade diamond, the flaws are only going to detract from the diamond’s value, not its appearance.