The system was developed for assessment of the clarity of the diamonds used in jewelry. While in the progress of development the clarity grading system was called 'diamond grading and evaluation appraisal'. The key aspects of the grading system were - color, clarity and make (quality of the cut, polish and finish).

Even though there were some other grading systems available for diamonds, there was no single system that was used as a standard across traders. Some of the classifications that were used before the formal development of the GIA clarity grading system were terms like Flawless, VVS, VS, SI and I.

But these classifications were not precise and clear and therefore it was very difficult to classify a diamond in one of these unequivocally.

In the early 1953, after the completion of the GIA clarity grading system, it was formally announced and made public.This initial system had nine grades and these included - Flawless, VVS1, VVS2, VS1, VS2, SI1, SI2, I1 and I2. The 'I' stood for Imperfect and was exactly the opposite of the Flawless diamond.

Though this new system of grading had been contributed to the industry, there was the need to popularise it. To practice the system, one needed to be trained in the nuances of evaluation process.

Soon after the GIA clarity grading system was unveiled, the first diamond grading class took place in April of 1953 by Liddicoat and Robert Crowningshield. New York was the venue of this first prestigious course. With a modest beginning that attracted only about 11 students from Massachusetts and Pennsylvania, GIA clarity grading courses are held in various cities and this learning is disseminated using various teaching methods like distance education, traveling extension classes and probably webex too.

The system developed in 1953 underwent its first change only in 1970 when the IF grade was added to the already present nine grades. This was done because Liddicoat realized that many diamonds were re polished to get the Flawless certificate, compromising on the symmetry and the proportions. (IF grade means Internally Flawless where the diamond can have some blemishes from outside but has to be flawless internally.)

Minor changes have been made to the system since then but the GIA Clarity Grading System was the first attempt to professionalize any kind of diamond clarity grading system. The efforts by Liddicoat and team have led to a more objective classification of the diamonds that are traded today and therefore made the industry more structured.

Reference : GIA Study Material ( Graduate Gemologist )