4Cs of Diamonds: Clarity

If you are just a beginner in a field of diamond jewelry then choosing one can be really a challenge. Of course, visually any diamond looks fabulous but once you ask about the gem you are bumped by hard-to-comprehend information with some letters and numbers you may know little about. So, in order you are not overwhelmed but rather be prepared, there is some information that can help you decipher strange letters in parentheses like SI, VVS, SI1, VS1, etc.

There are 4Cs of diamonds: cut, carat, color and clarity. While everything can be clear with cut – you choose it to your individual liking or that is the most beneficial for the certain jewelry design – and carat, let us focus on clarity aspect.

Even though diamond is often associated with a gem that is crystal clear as a tear, it is usually not. Most of diamonds have inclusions and the price usually depends on their amount. Only gemological laboratories can accurately define what sort and amount of inclusions are there inside the gem and provide this information in the certificate. There is a range of organizations offering such service but probably the most reputable is the Gemological Institute of America (GIA). So the GIA grading system today is the following:

GIA diamond clarity grading scale
Category Flawless Internally Flawless Very Very Slightly Included Very Slightly Included Slightly Included Included
Grade FL IF VVS1 VVS2 VS1 VS2 SI1 SI2 I1 I2 I3

The GIA diamond grading scale is divided into six categories and eleven grades. The clarity categories and grades are:

  • Flawless category (FL) diamonds have no inclusions or blemishes visible under 10x magnification.
  • Internally Flawless category (IF) diamonds have no inclusions visible under 10x magnification, only small blemishes on the diamond surface.
  • Very, Very Slightly Included category (VVS) diamonds have minute inclusions that are difficult for a skilled grader to see under 10x magnification.The VVS category is divided into two grades; VVS1 denotes a higher clarity grade than VVS2. Pinpoints and needles set the grade at VVS.
  • Very Slightly Included category (VS) diamonds have minor inclusions that are difficult to somewhat easy for a trained grader to see when viewed under 10x magnification.  The VS category is divided into two grades; VS1 denotes a higher clarity grade than VS2. Typically the inclusions in VS diamonds are invisible without magnification, however infrequently some VS2 inclusions may still be visible. An example would be on a large emerald cut diamond which has a small inclusion under the corner of the table.
  • Slightly Included category (SI) diamonds have noticeable inclusions that are easy to very easy for a trained grader to see when viewed under 10x magnification. The SI category is divided into two grades; SI1 denotes a higher clarity grade than SI2. These may or may not be noticeable to the naked eye.
  • Included category (I) diamonds have obvious inclusions that are clearly visible to a trained grader under 10x magnification. Included diamonds have inclusions that are usually visible without magnification or have inclusions that threaten the durability of the stone. The I category is divided into three grades; I1 denotes a higher clarity grade than I2, which in turn is higher than I3. Inclusions in I1 diamonds often are seen to the unaided eye. I2 inclusions are easily seen, while I3 diamonds have large and extremely easy to see inclusions that typically impact the brilliance of the diamond, as well as having inclusions that are often likely to threaten the structure of the diamond.
GIA clarity grading procedure

GIA clarity grading is performed under 10x magnification with darkfield illumination. The GIA Laboratory uses as standard equipment binocular stereo microscopes which are able to zoom to higher magnifications. These microscopes are equipped with darkfield illumination, as well as an ultraviolet light filtered overhead light. When grading is performed using a 10x handheld loupe, ‘darkfield’ illumination is more difficult to achieve. The grader must use a light source in such a way that the base of the stone is lit from the side, and the crown of the stone is shielded from the light.

After thoroughly cleaning the diamond, the diamond is picked up using tweezers in a girdle-to-girdle hold. The grader views the diamond for the first time through the table, studying the culet area of the stone for inclusions. The diamond is then set down, and picked up with the tweezers in a table-to-culet hold. In this position the diamond can be studied from the pavilion side, and the crown side, examining the diamond through each facet for inclusions. Once a sector of the diamond has been thoroughly examined the grader rotates the diamond in the tweezer, so that the neighboring sector can be examined. The grader uses darkfield lighting to reveal characteristics, and alternates to reflected, overhead lighting to ascertain whether a characteristic lies within the stone, on the stones surface, or both. If the grader is using a stereo microscope, they may zoom in to a higher magnification to make closer observations of an inclusion, but then return to 10x magnification to make an assessment of its impact on the clarity grade.

If a stereo binocular microscope has been used, a final assessment using a 10x loupe is performed before the final judgment is made on the clarity of the stone. The grader first decides the clarity category of the diamond: none (FL, or IF for a blemish), minute (VVS), minor (VS), noticeable (SI), or obvious (I). The decision is then made on the grade of the diamond.

The information is taken from http://en.wikipedia.org/wiki/Diamond_clarity#The_GIA_grading_system_today

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