Clarity indicates the presence or absence of inclusions within the diamond and blemishes on its surfaces. These slight birthmarks of nature can significantly affect the value of a diamond, depending on their sizes and locations. Truly flawless diamonds are extremely rare and very valuable.

The grades of clarity, as defined by the two most common certificate labs:

(Note that AGS still distinguishes between Flawless and Internally Flawless under the Comments section on the certificate.)

Flawless: No flaws visible under 10x magnification. Very expensive and rare. We have heard people wanting to buy one for engagement because it symbolizes a flawless, perfect match, but only you are ready to pay for it.

Internally Flawless : Only external blemishes visible under 10x magnification. Also very expensive and rare.

VVS stands for "Very, Very Slightly Included", and the flaws are tiny (pinpoint-sized) even under a 10x magnifying glass, and cannot be seen with naked eyes. VVS1 contains less flaws than VVS2.

VS stands for "Very Slightly Included", and the flaws are visible under a 10x magnifying glass. VS1 contains less flaws than VS2. Similar to color, some people just have better eyes and known to be able to see flaws in a VS2 with naked eyes, but generally speaking, the flaws cannot be seen with unaided eyes.

SI stands for "Slightly Included". SI2 is the threshold where flaws are starting to become "eye visible", and in diamond speak, SI1 and up are usually "eye clean". The EGL (European Gemological Laboratory) has an SI3 grade instead of an I1 grade, but they are essentially the same thing. This might be one reason why some people deem the EGL certificate "softer" than the GIA or AGS certs.

I stands for "Imperfect". Flaws are visible to the naked eye.

There are many different types of blemishes, like scratches, fractures, and chips. These blemishes are found on the surface on the diamond. The inclusions, on the other hand, are found inside the diamond. Typical inclusions are carbon spots (black spots inside a diamond), feathers (a crack inside), and pinpoints (small spots).

Clarity Treatments

Advance technologies make it possible to artificially treat the cracks and inclusions in a diamond. The most common technique is Laser Drilling, where they drill a tiny hole to remove inclusions. Fracture filling is another technique to fill feathers and cracks by injection. In 1998, both the World Federation of Diamond Bourses (WFDB) and the International Diamond Manufacturers Association (IDMA) adopted polices that required full disclosure for laser drilling.

The GIA lab does not accept clarity treated, or so-called "enhanced", diamonds for grading. The AGS Lab grades laser-drilled diamonds and discloses the fact on the "Comments" section, but it doesn't grade fracture-filled diamonds. Lab certificates for clarity treated diamonds are usually issued by EGL or the Global Gemological Laboratory (GGL). Remember that don't let any salesperson trying to sell you an enhanced diamond as a bonus quality!