The clarity of a diamond is one of its most important features, as it directly affects the stone's appearance and value. Five key factors determine the overall impact that an individual clarity characteristic has on a diamond's appearance and grade: size, number, position, nature, and color or relief. Each of these factors plays a significant role in determining the clarity grade, and their relative importance can vary from diamond to diamond.
The size of a clarity characteristic has a direct correlation with its visibility. Generally, larger and more visible characteristics lead to a lower diamond clarity grade. Additionally, large inclusions may threaten a diamond's durability. In diamonds with inclusions of varying sizes, the grade is typically established by one or two of the larger inclusions, while smaller inclusions have little impact on the grade.
Although a higher number of clarity characteristics can lower the grade, the grade is usually determined by the visibility of the characteristics rather than their quantity. For instance, a diamond with numerous minute pinpoints may still qualify as very very slightly included (VVS), while a single large, dark, or centrally located included crystal could lower the grade to very slightly included (VS), slightly included (SI), or even included (I).
The position of inclusions within the diamond greatly influences their visibility. Inclusions directly beneath the table are the most visible, while those under the crown facets or near the girdle are more difficult to see. Consequently, diamonds must be examined from multiple angles to identify all characteristics. An inclusion's position can also determine its potential to cause damage. For example, a feather might enlarge over time, but those reaching the pavilion are generally protected by the mounting. Feathers extending to the girdle or crown, however, may grow if the diamond strikes a hard surface.
The nature, or type, of a clarity characteristic informs whether it is an inclusion or a blemish and whether it poses any risk to the diamond. Most characteristics do not pose a risk, as stones with durability issues often do not survive the cutting process. However, the size and location of an inclusion can influence its effect on durability.
Color or Relief
Color and relief can impact the visibility of a clarity characteristic as much as its size. In general, inclusions that differ in color from their host diamond are more noticeable. The greater the contrast between the inclusion and the diamond, the more it will affect the clarity grade. Colored inclusions can lower the grade more than colorless inclusions, although black pinpoints may be more difficult to see than white ones.
GIA Diamond Grades:
Internally Flawless (IF)
IF diamonds display external imperfections and no internal inclusions when inspected by a proficient grader under 10X magnification. GIA introduced this grade in the 1970s to classify diamonds that do not fulfill the strict criteria for the Flawless grade. Generally, IF diamonds' blemishes can be eliminated through minor repolishing, with light surface graining being an exception as it cannot be removed in this manner.
Very Very Slightly Included (VVS1 and VVS2)
VVS diamonds have minuscule inclusions that are challenging for an expert grader to detect under 10X magnification. Inclusions in VVS diamonds are either extremely difficult to see when the diamond is face-up or only visible through the pavilion. In VVS diamonds, inclusions are very difficult to spot.(The GIA system employs terms such as "extremely" and "very" to indicate subtle variations in difficulty or ease of observing inclusions.)Under 10X magnification, a typical VVS stone may display a pinpoint or two, or reflective internal graining visible solely through the pavilion or very faintly through the crown. If these features appear more distinctly through the crown, the stone would receive a VVS grade. Surface-reaching inclusions like bearded girdle, chips, or tiny bruises may determine the grade as either VVS1 or VVS2, depending on their size and face-up visibility.
Very Slightly Included (VS1 and VS2)
VS stones contain minor inclusions that vary from difficult (VS1) to somewhat easy (VS2) for a trained grader to observe under 10X magnification. Typical inclusions consist of small enclosed crystals or feathers, distinct clouds, and clusters of pinpoints that do not impact the stone's aesthetics. In rare instances, a VS stone may contain an inclusion visible to the naked eye. The size, nature, position, number, and color or relief of the inclusion should be considered in relation to the stone's size and shape. For example, an emerald cut over one carat in size may have an eye-visible enclosed crystal beneath the table's corner and still be within the VS range.
Slightly Included (SI1 and SI2)
SI stones feature noticeable inclusions that are easy (SI1) or very easy (SI2) for a trained grader to identify under 10X magnification. Common inclusions include enclosed crystals, clouds, and feathers, which are typically centrally located.
As with the VS range, a stone with an eye-visible inclusion can receive an SI grade, but generally, the characteristics in an SI diamond are not visible face-up without magnification. Eye-visible inclusions are more common in SI stones.
Included (I1, I2, and I3)
Diamonds in the I range possess inclusions that are evident to a trained grader under 10X magnification. One or more of the following are characteristic of these inclusions:
They are visible face-up without magnification
They significantly impact the stone's durability
They are numerous or large enough to affect transparency and brightness
In conclusion, the five clarity factors—size, number, position, nature, and color or relief—play crucial roles in determining a diamond's overall appearance and grade. While each factor contributes to the clarity grade, their relative importance may vary from one diamond to another, reflecting the unique characteristics and individuality of each stone. Understanding these factors can aid in the proper evaluation of a diamond's clarity and ultimately, its value in the market.