Diamond color is an ironic name for one of the 4Cs since it actually refers to the absence of color. So on the diamond color scale, the less color the better grade the stone gets.
Many people seem to think there is an association between a diamond's color and clarity when in fact have nothing to do with one another in terms of the 4Cs.
Diamond clarity measures the imperfections (flaws and inclusions) in the stone while color only refers to the color of the stone.
The confusion may be the result of clarity being interpreted as "clear" and "clear" being associated with colorless. Or it may be that both of these attributes are graded and measured by what is NOT there rather than what is.
In this case, the less color the more valuable the stone.
Of course we've all heard of pink, purple, and blue diamonds to name a few (just ask Mariah Carey) but those are considered fancy-colored diamonds not white diamonds which is what the GIA scale measures.
Fancy colored diamonds sit outside of the color range we're discussing here and are not included in the standard color chart—they are very rare and very pricey and unlike white diamonds, are judged based on the intensity of color rather than the absence of color.
Engaging Fact: Diamonds that have a color other than clear are called "fancy colors" and cost a pretty penny. J. Lo's 6.1 carat rock from Ben Affleck was a pink diamond worth apparently $1.2 million. It's back at Harry Winston's if you have the dough.
Each grade is assigned a letter value going from D (which means colorless) to Z (which is referred to as near-colorless or light) and has a range of benchmark colors associated to it.
Check out the video to see GIA's description of their diamond color scale.
The GIA scales help us compare one diamond to the next and are a great guide for diamond shopping.
Keep in mind that a jump from one letter to the next (even within a grade) can mean a difference of thousands of dollars and reflects on the 'quality' of the stone.
The 'theory' behind diamond color is that the more color a white diamond has, the less it will shine.
Now let's move on to the next of the 4Cs: Carat Sizes & Charts.