The GIA clarity grading system was proposed and developed by Richard T. Liddicoat in 1952 when he was the president of the GIA. He worked on this system with the support of Lester Bensen and Joe Phillips and was assisted by Robert Crowningshield and Bert Krashes.

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.

Early in 1953, when the GIA system was developed completely the GIA clarity grading system was formally revealed and shared with the world.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.

In april 1953, Soon after revealing the GIA clarity grading sytem, the first diamond grading class was started by Liddicoat and Robert Crowningshield. The place of this first distinguished course was New York. 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 )