DIAMOND GRADING: IS IT A SCIENCE?

I’m often asked if diamond grading is an exact science. In other words, if one grader calls a diamond a VS-1, is every grader going to call it a VS-1?

My answer would be that diamond grading is a scientific, subjective analysis using distinct parameters to judge by. A close analogy to the process would be the judging and grading of an athletic event such as a diving competition in the Olympic Games.

In an Olympic diving competition, there are eight or nine judges who will grade the dive. These judges are well trained in what makes a “perfect” dive, and they take off points accordingly for any “imperfections” in form or execution. Their analysis however, is subjective, so when they all “hold their cards up” there might be a slight difference in grade from judge to judge. For the most part though, they will be in close agreement.

It is the same with diamond grading. If you take eight or nine qualified gemologists and have them grade the same diamond, their grades should ordinarily closely agree, with possibly a couple grading slightly higher or lower. If you have a diamond that is a “borderline” grade, half the graders may call it a (low) VS-1 and the other half may call it a (high) VS-2. This is to be expected, and in reality usually affects the value level relatively slightly.

CLARITY:



SI3: Outside of the GIA Diamond clarity scale is a grade you may have seen called SI3. The Rap Sheet, which is a Trade Publication, honors the SI3 grade given out by EGL, the European Gemological Laboratory. The grade has also been endorsed in a year 2000 meeting of the World Diamond Congress, and accepted by the World Federation of Diamond Bourses. It is described as a split between the SI2 and I1 clarity grade, and is used by Sarasota Gemological Laboratory when warranted.

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