Before GIA generalized the D to Z color grading scale, all systems were roughly used. Classification by A, B, C without clear definition, descriptive such as Arabic numerals (0, 1, 2, 3), Roman numerals (I, II, III), “gem blue”, “blue white” Terms and so on. These were misunderstood and did not have a good reputation. Therefore, the creators of the GIA color scale wanted to create something new that was not related to the previous system. Therefore, the GIA scale starts at D. Very few people still stick to other grading systems. No other system is as clear and generally accepted as the GIA scale.