If you look closely though, you notice something that lacks an obvious explanation: the color grading system starts from D and follows through to Z. What about A, B, and C, then?
The London Diamond Syndicate was the first to start sorting through rough diamonds meant for sale. From then and up until the 1940’s, traders used a variety of systems to specify diamond color: letters (with more than one A for the better stones – AA, AAA, etc.), Arabic (0-9), Roman numerals (I, II, III, IV, etc), and even descriptions like “river”, “Golconda”, “cape”, “jagers”, “blue-white”, and others.
It is easy to imagine the confusion this quickly caused, and when the GIA stepped in, everyone was decidedly relieved. The new system they brought in was a fresh start and started off with the letter D. Now, every diamond expert in the world follows this system, and most admire its accuracy and efficiency. You too probably felt its usefulness first hand when buying your favorite diamond infinity engagement ring.