The best grade for diamonds, according to JannPaul, begins with D, followed by E, F, G, and all the way to Z. A D-grade stone is flawless, clear and colourless. As you go down the grades, less valuable ones have an obvious hint of yellow, which is not the same as in fancy yellow diamonds. To judge the colour of your diamond clearly, place it next to a spectrum of others graded from D and so on. Look at it from the side, while it lies on a sheet of white paper, and under fluorescent lighting. If your budget is tight, a lesser grade may save you a f ew dollars. The trick? Set your diamond in yellow gold, so the yellow tinge is not so obvious.