The GIA grades diamonds on a scale of D (colorless) through Z (light color). All D-Z diamonds are considered white, even though they contain varying degrees of color. True fancy colored diamonds (such as yellows, pinks, and blues) are graded on a separate color scale. Unless held side by side, it can be difficult for even the most trained eye to discern a D from a F.
Color becomes much harder to detect once a stone is set in a ring and placed in an environment that contains color (as opposed to the all white background used in diamond color grading). For instance, an H color diamond may look as colorless as an F when set in a ring under normal lighting conditions, especially if the two are not compared side by side.
Another factor that affects a diamonds’s apparent color is the color of the mounting itself. Yellow gold makes slight amounts of yellow in a diamond less obvious, while white metal mountings make the color in yellow diamonds more apparent.
Color becomes more important as carat weight increases, because color is easier to perceive in a larger diamond, just as a carafe of white wine shows more color than a single glass.
For the best value in what would appear to the naked eye as a colorless diamond, look for G-J diamonds. Because color is easier to detect in larger diamonds, opt for G-H in diamonds over one carat, and I-J for those under one carat. Once set in a ring, these diamonds will look just like higher color grade diamonds. Instead of investing in higher color, invest in higher cut, the most important factor in a diamond’s brilliance.
Because diamonds with more facets reflect more light, they tend to hide color better than other shapes. Consider round, princess or other modified brilliant cuts over step cuts such as emerald or asscher if you are concerned about color.
If you are concerned primarily about carat weight, and are on a tight budget, consider a yellow gold setting and a round diamond in the K-L color range. A lower color diamond with a higher cut grade will have more sparkle and visual appeal than a higher color diamond with a lower cut grade.
If, while shopping for a diamond, you are ever given a color range (e.g. G-H) as opposed to a specific grade, the diamond is not certified by GIA. The seller is only estimating the diamond’s color using GIA terminology.