The quality of the cut is arguably the most important factor in determining a diamond’s beauty. Over the years many people have gotten the impression that a diamond’s clarity merits a great deal of emphasis. Truth is, as long as a diamond shows no visible inclusions to the naked eye, its clarity doesn’t show. How well a diamond is cut, however, most determines the beauty to everyone who looks at it.
Determining a diamond’s cut grade is not an exact science. The American Gemological Society has by far and away the most intricate grading system, analyzing the most factors. It is also the most complex grading system. What the AGS grades as a Triple Zero Cut (using a zero to five sliding scale, zero being the best) is a top of the line Ideal Cut in anyone’s book (with rare exception). The GIA labs (Gemological Institute of America) use an entirely different grading system: Excellent, Very Good, Good, Fair, Poor.
All of this to say, there are different definitions within the industry about what defines an Excellent or Ideal Cut, even amongst the top, most respected labs. And that’s to say nothing of all the different labs that are grading diamonds these days. Generally speaking, one can loosely define the various cut grades as I’ve done below: