Diamonds Education

GIA Cut Grade for Certified Diamonds

If you’ve ever purchased a diamond solitaire, you’re most likely familiar with the “4C’s” of diamond grading – cut, clarity, carat, and color. Until the recent development of the Gemological Institute of America’s Cut Grade, a certified diamond’s cut has been the most widely debated of this diamond grading criterion.

A diamond’s cut is the only grading criterion not determined by the natural characteristics of the stone. Contrary to most assumptions, the cut of a diamond does not refer to the shape of the stone, but to its proportions (width and depth), polish, symmetry, and facet uniformity. It’s these factors that determine the diamond’s levels of brilliance, fire, and scintillation.

A diamond’s brilliance is determined by its ability to reflect white light back to the eye, and its fire is its ability to reflect colored light. Scintillation, or a diamond’s sparkle, is a combination of the stone’s brilliance and fire, resulting in “flashes” when a diamond moves in the light. With shallow cuts, light is lost through the bottom of the stone, and with deep-cut diamonds, light escapes out of the sides. The most expertly cut diamonds reflect light back to the surface, bringing the brilliance of the diamond to the forefront as it sparkles in your engagement ring.

The Gemological Institute of America (GIA) is a non-profit organization whose mission is to ensure public trust in gemstones. Recognized as the foremost authority in gemology, the GIA has recently developed its Diamond Cut Grading, which categorizes each loose diamond’s cut grade as excellent, very good, good, fair, or poor.

The GIA’s Diamond Cut Grading System for round, brilliant cut diamonds is a comprehensive grading system based on fifteen years of extensive light-behavior computer modeling and statistical information gathered by more than 70,000 human observations. This scientific assessment accurately defines the factors of a round brilliant diamond. While many of these were already well known in the diamond industry, some newly discovered factors resulted in techniques that produced quality diamonds from stones that were previously thought unusable.

For loose diamonds, the GIA’s rating system grades a brilliant cut diamond’s face-up appearance, using light-behavior computer modeling and algorithms to predict brightness, fire, and scintillation. These measurements, along with the diamond’s durability, polish, and symmetry, determine the GIA Diamond Cut Grade.

More than 99% of the diamonds graded will fall into Diamond Cut Grades of excellent, very good, or good. A range of characteristics and proportions define each grading parameter. The GIA Diamond Cut Grading System is designed to educate consumers, arming them with the confidence they need when making diamond purchases. If you purchase a certified diamond graded as “Excellent”, you can rest assured you’ll receive an exquisite stone with high levels of brilliance, fire, and scintillation.

Although the GIA Diamond Cut Grades are currently assigned only for round, brilliant cut diamonds, the GIA is currently researching diamond cut grades for emerald and princess cuts, and will share this data with the diamond industry when their research is complete.

At Brilliance, we offer GIA certified diamonds with cut grades ranging from Excellent to Fair to ensure the largest selection.