While some sellers of diamonds will tell you that “Beauty Is In The Eye Of The Beholder”, any professionally trained gemologist will tell you that brilliancy, fire, and sparkle are essential for beauty in a diamond. No matter what else the diamond has with regard to Cut, Color, Clarity, or Carat Weight...if it is not brilliant, it can’t be beautiful. For almost 100 years gemologists have been taught to measure brilliancy by calculating the path of light that occurs in a diamond. That is, by calculating the angle of reflection, the angle of incidence, and the critical angle, brilliancy is theoretically determined. But there has never before been a machine that could actually measure the light return from a diamond. Now there is a new machine that can do that. It is called the Beauty Grade® machine and it is the first machine that actually measures the light return from a diamond. The higher the Beauty Grade® number, up to 100, the better. It is the most important number you should know when buying a diamond because it is a direct measurement of the efficiency of the light return of the diamond.
There are two major grading systems in use now. The GIA system designates color grades from D to Z and clarity grades from Flawless to Imperfect 3. Prior to 2006, the GIA had no cut grade on their Reports. Only recently has the GIA come out with a cut grade and the GIA cut grade system is very broad with only 5 categories. As GIA has stated, customers will see visible differences in performance from diamonds in the same cut grade. The other system is the AGS system, which grades on a scale of 0-10, with 0 being the finest and 10 the poorest. This is a more advanced and complete system because it fully grades the diamond for cut as well as color and clarity. Thus, an AGS 0/0/0 is the highest grade you can buy. Both systems were originated by Robert Shipley, the Father Of American Gemology, and the founder of both the GIA and the AGS. The GIA system is much more widely used, but is also much more widely misused. That is because the system is based on letters of the alphabet and is not trademarked or protected. So anyone who wants to use the system can do so, whether qualified or not...and many do. By contrast, the AGS system is much more comprehensive and is copyrighted, so its use is somewhat protected and can be legally used only by AGS members with gemological training. Additionally, the AGS system includes a more detailed cut grade, the most important factor that governs diamond beauty and value.
But even though the AGS system is more accurate than any of the other labs, it still grades in ranges, within which there can be differences in performance and beauty. For example, a cut grade of “0” covers the range of 90 to 100, much like the grade of “A” is a score of 90 to 100, but obviously a grade of 100 is better than a grade of 90 (which is only a fraction away from the next lowest grade). So it is possible for a diamond to be at the bottom of the bracket (90) in all three categories of cut, color & clarity, and still earn a grade of 0/0/0. Obviously, a diamond graded 0/0/0 because of 100/100/100 is much more desirable than a 0/0/0 because of 90/90/90. That is why the AGS Document advises the reader of the Document to consult a Certified Gemologist for guidance and advice when actually selecting a diamond.