Why do diamond grading for colour start with a D, but not with a A?
Before there was a standardized grading system for diamond color, retailers would tell their customers that this diamond was a grade A, B, or C diamond. However, there was no consistency from one jeweler to the next as to just what these letters really meant with respect to the color of the diamond. So, when a standardized system was introduced, it started with D to avoid confusion with the older nonstandard grades.
