There are numerous grades based on each of the four "Cs," preventing the large value changes between the grades that would arise if there were only a few. This keeps the changes in value in check.
The Gemological Institute of America has determined the grades and their results listed below (GIA).
Clarity grading scale:
The scale for grading clarity ranges from stones that are visually flawless to those that have many obvious inclusions.
Color grading scale
The most typical color tint for "white" diamonds on the color grading scale is yellow. Starting at "D" for colorless and going all the way up to "Z" for light yellow, this scale assigns grades to colors based on how much yellow is present.
