Clarity is the measure of how clearly a diamond is able to allow light to pass through it, reflect off of it, and refract within it. This light quality is determined by a number of factors, one of which is the level of flaws, both internal and external. The internal flaws are referred to as inclusions, and the external flaws are known as blemishes with inclusions more often being the more detrimental of the flaws.

All diamonds contain features, or flaws, such as mineral inclusions and fractures, and most flaws can be so slight as to have no effect on the diamond's ability to transmit and scatter light. However, larger flaws, and large groupings of flaws, can diminish the ability of light to pass through the diamond unimpeded. The location and coloration of the flaw has tremendous impact on the overall impact on the diamond's clarity. If a flaw is located near the center of the diamond, and is dark in color, it will often be more detrimental to the diamond's clarity than a clear flaw closer to the diamonds edge.

Clarity is the one area where you will find that you can sacrifice a certain measure of perfection for the sake of cost, and still have a diamond that you will love and cherish. Clarity has tremendous impact on the final cost of the diamond, as it is one of the 4 Cs taken into account with the assessing of a diamond's characteristics, as well as determining a diamond's monetary value. A scale for clarity is used to assess exactly where a particular diamond stands within the world of diamonds. The grading system has been devised to measure the amount of imperfections within diamonds, based on size, location, quantity, color and nature of the inner flaws, or inclusions, when viewed under a magnification of 10X.

Inclusions need not be looked upon with disgust, however, as small inclusions, which detract negligibly from a diamond's clarity and brilliance, can serve as distinct markers for an individual diamond, as no two diamonds share the same inclusions or inclusion patterns. It is for this reason that it is important to become familiar with the inclusions within your diamond, as they serve as the diamond's fingerprint. Knowing your diamond's distinct characteristics will allow you to properly identify your diamond should it leave your person, whether to be cleaned, to be appraised, or for any other reason.

The scale that is most commonly used to determine a clarity grade for diamonds is the GIA clarity grading scale. This grading scale runs from F to I. All diamonds of gem quality need to be graded on this scale in order for the diamond's value to be assessed properly. The scale runs as follows:

1. 1FL: Flawless
2. 2IF: Internally Flawless
3. 3VVS1 and VVS2: Very, Very Small Inclusions (two separate grades)
4. 4VS1 and VS2: Very Small Inclusions (two separate grades)
5. 5SI1 and SI2: Small Inclusions
6. 6I1, I2 and I3: Inclusions Visible

There is also a grade of SI3 (Small Inclusions 3), but this is used primarily by the EGL (European Gemological Laboratory), and is not recognized by the GIA (Gemological Institute of America) or the AGS (American Gemological Society).

The actual names of each grade are simple to understand. They simply reflect the amount of internal flaws (inclusions) and external flaws (blemishes or occlusions) visible to a trained professional diamond jeweler under a 10x loupe or magnification.

Due to the processes involved in the formation of diamonds, diamonds, as with all naturally occurring substances, are prone to impurities. These impurities are formed during various points in the long life of the diamond, from its creation within molten rock, where many other surrounding minerals can become trapped within the cooling diamond crystalline structure, to the cutting and polishing of the diamond by master gem craftspeople. It is these processes that create conditions that allow for numerous flaws that can be found in and on diamonds. These flaws are split into two primary categories, inclusions and blemishes. Familiarity with these two categories and the nomenclature involved with these flaws will help you to understand why one diamond is more costly than another.

The most widely used and accepted clarity grading system is one that was introduced by the Gemological Institute of America (GIA) in the early 1930's. The grading system ranks diamonds from "F", or Flawless, to "I", or Imperfect, with most grades having sub-grades, as in: I1, I2, I3, corresponding to Imperfect 1, Imperfect 2, Imperfect 3. Each sub-group is extremely close to one another, and each is only able to be differentiated between by an experienced diamond grader using a magnification of 10X. As may already be apparent, the closer a diamond is to a grade of "F", or flawless, the more rare, and more expensive, the diamond.

The two types of flaws looked for are: 1) Blemishes, or exterior scratches, such as might be found naturally or from polishing; and 2) Inclusions, or inner-flaws, such as breaks (or feathers), mineral crystals, or even drill holes made by a laser in order to have removed another inclusion. Inclusions are the most common flaws due to the fact that blemishes, such as naturals found on a thin girdle, can often be polished away.

Flawless (F): This indicates that there are no noticeable inclusions or blemishes in or on the diamond when looked at by an experienced diamond grader under a magnification of 10X. These are the most rare of diamonds, and so carry a much greater cost than diamonds of lesser clarity grading, with all other aspects of the diamonds being equal (i.e., same cut, color and carat). . A diamond can still be graded as F or flawless if it has extra facets on the pavilion, or if there are small naturals on the girdle only (this applies only if the girdle is thin). There is one notable difference between American and European grading of flawless. In American grading, the diamond must be, as mentioned previously, internally clean (free of inclusions) and externally clean (free of blemishes, or at least having only blemishes which can be polished away) in order to be termed flawless. In European grading, however, a diamond must only be free of internal flaws in order to achieve the grade of F. These are extremely rare and sought after diamonds. The purity grade for an F is 99.999

Internally Flawless (IF): This clarity grade of diamond is only slightly less rare than the flawless grade. This grade indicates that the particular diamond has absolutely no visible internal flaws when viewed under 10x magnification under the proper conditions. As with Flawless (F) diamonds of this grade are more expensive than diamonds of a lesser clarity grade, all other conditions being equal. There can be minor flaws on the outside of an IF graded diamond as long as they can be polished away.

Very Very Small Inclusions (both 1 and 2) (VVS1, VVS2): The VVS1 and VVS2 are close to the same grade of diamond, with only an experienced diamond grader being able to differentiate. As the name implies, this grade of diamond has minor internal flaws. These flaws can be seen by a professional under 10x magnification, but are so difficult to see as to be nearly non-existent. In the case of brilliant diamonds, such as the round brilliant or princess cut, these flaws are very insignificant, as only trained professionals can find them under 10x magnification. In the case of step cuts, such as the emerald cut, this is a good grade to consider as perfect to prevent from any inclusions being visible due to the simple mirror-like facets. As far as the difference between the VVS1 and VVS2, if an inclusion is detectable by a grader under a loupe from the bottom up, it would be considered VVS1, whereas if an inclusion can be detected from the table down, it would be considered a VVS2. The grade difference between a 1 and a 2 can be quite difficult for even an experienced grader to differentiate, as can be illustrated by their purity grades of 99.99 for a VVS1 and 99.98 for a VVS2.

Very Small Inclusions (both 1 and 2) (VS1, VS2): As with the very very small grade, the very small grade is self-descriptive. The flaws within this grade of diamond are visible by a professional under 10x magnification, but they are still difficult to find, and invisible to the naked eye. VS1 and VS2 grades are 99.9 pure and 99.8 pure, respectively. The expense reduction involved with this clarity grade of diamonds makes this a good selection for a fine diamond with excellent clarity.

Small Inclusions (1, 2 and 3) (SI1, SI2, , according to the EGL, SI3 ): This is the grade where flaws can be readily seen by a professional under 10x magnification, but can still be invisible to the naked eye, with the two sub-grades (the third sub-grade, SI3, not being recognized by the GIA) being 99.0 pure and 97.0 pure respectively. SI2 is typically visible to the naked eye, while SI3 can almost always be seen by the unaided eye. This grade of diamond can provide an excellent source of savings when purchasing a diamond.

Imperfect or Inclusions Visible (1, 2 and 3) (I1, I2, I3): In this grade of diamonds the internal flaws of the diamond are easily visible under 10x magnification, even to a non-professional, and are visible to the naked eye. The problems occurring with this grade are possible interference with the light qualities of the diamond due to the large flaws. To illustrate this point, an I1 is 85% pure, and I2 is 39% pure, while an I3 is 0.0 pure. For jewelry, an I2 and I3 should never be used, as even an I1 can have inclusions that can noticeably obscure the clarity and brilliance of the diamond.

It is not necessary to set your goal at the Flawless and Internally Flawless grades, as these are not only going to precipitously raise the cost of the diamond overall, but a flawless clarity is not necessary to have a beautiful diamond. Be aware that the grade that appears on a certificate for a given diamond is a result of the diamond being observed by a minimum of three trained professionals viewing the diamond under 10 X magnification, all of which is conducted under laboratory conditions.

You can save a great deal of money by simply looking at the grade of diamonds known as "eye clean". The "eye clean" grades on the clarity grading scale run from VVS1 to VS2, with some of the SI1 grade of diamonds being "eye clean". "Eye clean" simply indicates that while there may be inclusions present, they cannot be seen with the naked eye, and are thus unimportant.

The placement of inclusions that may be visible is also important in that, the setting of the stone, when chosen carefully and utilized by a skilled jeweler, can hide a diamond's flaw or flaws and can actually make them innocuous and irrelevant. So by finding a lower clarity diamond with no inclusions in the table, the diamond will appear clean once mounted properly.

If you are looking for a step cut, however, clarity is far more important, as flaws are more apparent and you should therefore go with a clarity of no less than a VS2.