Letter grades often are associated with color-- that is the case for finding the best regular or even black diamonds. But for jade, Grade A instead refers to the level of treatment it’s undergone before being sold. Grade A refers to untreated, natural jade and is considered the most valuable. In my list, however, I’ve also included Grade C, which means the color has been added to enhance the jade. While less valuable, keep in mind that it does not mean that treated jade is of lower quality in terms of durability.