Diamond clarity is one of the four Cs of diamond grading. Clarity refers to the existence and visual impact of inclusions and blemishes. Inclusions are internal flaws which can include other crystalline structures, part of smaller diamonds, cracks, and pieces of carbon. Blemishes are located on the surface of a diamond and can be the result of polishing. The number, location, and size of the inclusions and / or blemishes can affect the diamonds clarity grade.

A clarity grade delineates the overall appearance of the diamond under ten time magnification. Clarity grade is usually part of an extensive report that speaks to the quality of a diamond.

Independent gemological labs such as Geological Institute of America, American Gemological Society (AGS), and International Gemological Institute (IGI) examine a cut diamond and provide specific information about each individual stone. This information is helpful to jewelers when establishing pricing and for insurance purposes since each stone will have its individual set of unique “fingerprints”.

Today, the GIA clarity grading system consists of the following categories:

Flawless (FL): no inclusions or blemishes are visible at x10 magnification.

Internally Flawless (IF): no inclusions are visible at x10 magnification. Some small blemishes.

Very, Very Slight Inclusions (VVS1 and VVS2): the stone has minute inclusions that are very difficult to see under x10 magnification. VVS1 is a higher grade than VVS2.

Very Slight Inclusions (VS): the stone has minor inclusions that are difficult to see under x10 magnification. VS category inclusions are divided into VS1 and VS2. VS2 inclusions can sometimes be visible by a skilled gemologist without x10 magnification.

Slightly Included (SI): the stone has noticeable inclusions that are easily seen under x10 magnification.

Included (I): the stone has inclusions that are clearly visible under x10 magnification. These diamonds usually have inclusions that might threaten the longevity and durability of the stone such as clacks, definite crystalline structures. Included diamonds are not as brilliant.

When a diamond is assigned a clarity grade, there are five common factors that must be taken into consideration by all skilled diamond graders: size, number of inclusions, position, nature, color or relief. In order to provide the best assessment of the clarity grade, the diamond needs to be loose (unmounted) as the setting might abstract inclusions and blemishes and influence the graders decision.

There are a number of labs that will grade mounted diamonds. These assessments should be used as only as a guideline when establishing the value of a diamond.

Size: assesses the relative size of the inclusion / blemish. The larger the area of the flaw, the lower the clarity grade.

Number: assesses the number of flaws in one area. This is also referred to as a “cloud”. A number of pinpoint inclusions, fractures, or feathering in one area will create a cloudy appearance decreasing the brilliance of the stone. The larger the number of flaws in an area, the lower the clarity grade.

Position: depending on where the flaw is located may impact the overall clarity grading. Inclusions that are located under the table close to the pavilion will reflect multiple times creating an illusion of multiple flaws. This type of inclusion is known as a “reflector”. A reflector will only be noted once on the clarity grading report although it will be visible in multiple locations in the diamond.

Nature: nature on the flaw delineate the location (internal or external). Internal flaws automatically exclude the diamond from the Flawless category and Internally Flawless category while external characteristics will exclude the diamond from the Flawless category only. Nature of the flaw determines whether the inclusion poses a risk to the durability of the stone.

Color or Relief: this category assesses the color, relief, or both. Flaws that contrast with the surrounding stone are said to have “relief”. Colored inclusions contrast the most with the surrounding stone and therefore impact the clarity grade more.

Diamonds that are considered flawless are rare and extremely expensive. Technically speaking, even a flawless diamond will have flaws which speak to its origin and serve as gemological “fingerprints” that help with identification of the stone should it be stolen.

Although each lab has its own system of grading the clarity of a diamond, GIA clarity grading system is highly thought after. GIA is known to be the most unbiased gem grading laboratory while others have been known to skew the results in favor of the seller.