Knowledge Quest Series – CLARITY

Grading the quality of diamonds is unlike most grading systems – coins, stamps and other items are graded mostly for their lack of wear. Diamonds are graded for the lack or presence of natural inclusions and blemishes that nature created along with the diamond. Since buyers are willing to pay more for diamonds that are clean – lacking inclusions – than for spotted stones, the less the better.

Tools of the Trade

Firstly, the process may have subjectivity involved but that does not mean it is without guidelines and trade accepted procedures. For example, examining diamonds for grading purposes involves using magnification of 10x. What does that mean, you ask? Well a 10x power lens magnifies ten times, therefore the diamond will be ten times larger than its actual size.

Is that all? No. The lens, or loupe as it is called, must be corrected for color and distortion – called achromatic and aplanatic. Gemologists and diamond people keep loupes ready for action like a coach and his whistle.

Microscopes are now commonplace as loupes. The type used by gemologists are stereo, binocular with is called dark-field illumination. A dark area lies directly below the gem with the light in a 360 degree ring on the side of the dark area but below the stone. Power is from 10x to 80x or so. The higher power is used to identify inclusions and other pertinent features but not for grading.

The Lineup

Flawless (FL) is the top grade. It is a grade where at 10x no inclusions are seen – by someone competent in grading diamonds. Another grade, Internally Flawless (IF) is the same as Flawless except it is also without blemishes. Keep in mind that inclusions are inside the diamond and blemishes are on the outside. Beware that some foreign versions of the grades are with different standards and we are referring to the most accepted standard, that of the Gemological Institute of America (GIA).

The next grade set is that of Very Very Slightly Included (or Imperfect). However, the grade is stated as VVS1 or VVS2 – without an I included in the grade designation. The original grading system introduced in 1953 had the I and it meant imperfect. He trade did not like this added factor and the system was modified. The 1 is a higher (or better) grade than 2. In a VVS1, one may encounter a hard-to-see pinpoint in a location that is not in the center. VVS2 may have two pinpoints, for example. Keep in mind that with any diamond commanding this grade, inclusions cannot be seen with your eye alone – you will need a loupe or microscope and then it is very difficult.

The next grade set is that of Very Slightly Included (or Imperfect). Again, the I is left out in the grade designation. Again, a 1 is a higher grade than a 2. In a VS1, it is difficult to see but readily found. For example, a small colorless crystal located on the outer perimeter of the diamond, near the bottom might be a VS1. Move that same crystal up into the top area of the diamond, a VS2 may be more appropriate. Two small inclusions, if not located in the heart of the diamond, may command a VS1 or VS2 grade. Again, these are grades that the unaided eye will not be able to detect. Again, the inclusion is difficult to recognize.

The next grade set is the slightly Included (or Imperfect) diamonds. The inclusion may be centered in the heart of the diamond. It does not interfere with brilliance, etc. With an SI1 the inclusions may be observed without magnification if one views it from the pavilion, or face down, on a white piece of paper. With the SI2 grade, the inclusion can be seen in the face-up position.

The lowest grade set is the Imperfect diamonds. Inclusions usually are dark, easily seen and in the lowest grade (I3) even interfere with beauty, brilliant or create areas void of light.

Conclusion

Diamonds are clarity graded based on the lack of or presence of inclusions or blemishes. The size, number, location, nature, visibility and color of the inclusions are all taken into consideration when assigning a grade.

Some Personal Thoughts

We find it ironic that the trade encourages everyone not to call inclusions “flaws” but at the same time provides a clarity grade of flawless. Additionally, GIA revised their clarity system to eliminate the “I” (Imperfect) in the top grades of VVS and VS but retained it in the lower grades of SI and I. We prefer stating the “I” as meaning “included” instead of “imperfect” – not because it is a euphemism – but because inclusions are the basis for clarity grading.

Many people call the black spots in diamonds “carbon spots.” This seems odd to a diamond expert because diamond is carbon – the only gemstone that is an element. Since the inclusions in a diamond are usually not carbon but other minerals – olivine being the most common – carbon spots are very rare and not really noticeable as easy-to-see spots. In fact, often under a microscope, the dark inclusions are found to merely be refracting light away so they appear dark. We prefer to call them inclusions and leave the term “carbon spots” to collect dust in a pile of discarded diamonds terms.