The Gemological Institute of America (GIA) colour scale is the industry standard for diamond grading. The GIA diamond colour grades range from D (colourless) to Z (lightyellow or brown).
We measure the clarity of a diamond by its size and the number of inclusions and blemishes in or on it. Inclusions are interior irregularities and blemishes are exterior irregularities. These imperfections are not flaws, but rather the natural fingerprint of every diamond. With 11 grades, the system classifies a diamond’s clarity based on the nature, position and size of its inclusions and exclusions. The list below summarizes the GIA’s International Diamond Grading System.
Then coming to the ring, it's totally awesome.