Diamond grading scale by GIA
All diamonds are different but graded using the same diamond grading scale. The intrinsic qualities of a diamond are graded on carat weight, cut, clarity and color. The GIA has developed the diamond grading scale which has set the standard in the diamond industry, even as a benchmark for other diamond grading scales developed by other diamond grading labs. The diamond grading scale applies to the diamond color and clarity, and plays an essential role in determining the value of a diamond.
● Diamond grading scale: the clarity
On the diamond grading scale, clarity is assessed on a spectrum ranging from Internally Flawless to SI3, showing imperfections visible to the naked eye. In fact, most of the diamonds will have some degree of imperfection, it is part of the formation process every diamond goes through. Imperfections include inclusions internally and blemishes externally. The value of a diamond is largely dependent on the clarity assessed on the diamond grading scale. The fewer imperfections a diamond has, the rarer it is and the more valuable it becomes. Note that some diamond cuts like the Emerald cut have a tendency to show inclusions more easily while other diamond shapes hide it better.
● Diamond grading scale: the color
When color is assessed on the diamond grading scale, we, in fact, look at the absence of color. Colorless diamonds are very rare and have a bright brilliant sparkle. The color grading scale ranges from D to Z, where D is colorless and Z has a visible yellowish hue. This, however, does not apply to fancy colored diamonds. These are graded on a different diamond grading scale because the intensity of the color is more desirable in that case.
If you understand diamond color and clarity, you can start using the diamond price list. All diamond prices are listed on a Per Carat basis, arranged by carat weight. As the diamond color and clarity vary, so too does the Price Per Carat. As you will see, a 2 carat D color Flawless is much more valuable than a 3 carat J color SI2. Color and clarity are essential to the beauty, uniqueness, and price of a diamond.