to work on a new diamond grading system which they called the "diamond grading and evaluation appraisal". In 1953, they released their new system which assessed three aspects of diamonds; make, color and clarity. They took terminology used in the industry at the time and refined the definitions to produce a clarity scale by which diamonds could be consistently graded. The system at that time contained nine grades: Flawless, VVS1, VVS2, VS1, VS2, SI1, SI2, I1, and I2. The 'I' of the I1, and I2 grades originally stood for "Imperfect". During the 1970s, two changes were made to the system. Firstly, the Internally Flawless grade was added, as GIA noticed that many diamonds were being aggressively cut to remove any surface blemishes, and thereby reducing the cutting quality ("make") of the diamonds. The Internally Flawless grade gave diamond manufacturers a choice to leave blemishes on the surface of the stone, and achieve a grade higher than VVS1. The second change made to the grading system was the introduction of the I3 grade. This change was made in response to a growing number of diamonds of very low clarity being cut. The last change to the clarity grading system took place in the 1990s when the term "imperfect" was changed to "included". Modern GIA grading system 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 10× magnification. Internally Flawless category (IF) diamonds have no inclusions visible under 10× 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 10× 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 10× 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