The New GIA Cut Grade System
A simpler way for consumers to find the best cut diamonds
GIA recently announced the introduction of its Diamond Cut Grading System for round brilliant diamonds. Over the course of a fifteen-year research project, GIA researchers performed extensive computer modeling of round brilliant diamonds and conducted more than 70,000 observations on actual stones to validate the science. This system can now predict the cut grade for more than 38.5 million proportion sets. The result is a comprehensive Cut Grading System that accurately reflects all the critical cut factors of a round brilliant diamond.
GIA’s Diamond Cut Grading System assesses a diamond’s overall face-up appearance by using computer modeling along with other algorithms to predict levels of brightness, fire, and scintillation (sparkle and pattern) -- which indicate how well a diamond’s proportions work together to return white and colored light to an observer -- taking into account other important factors such as design (durability and over-weight) and craftsmanship (polish and symmetry).
For more information on GIA’s Diamond Cut Grading System, click here.
Grading Considerations
Although GIA Facetware® provides estimated cut grades based on all of the proportions and finish assessments of a standard round brilliant diamond, there are three main areas of grading that can be considered before using GIA Facetware® to estimate the potential cut grade. The tables below provide the highest possible GIA Cut Grade that can be achieved for various assessments of Girdle Thickness, Culet Size, and Finish (Polish and Symmetry); these are all quality elements of a diamond that are visually assessed by graders at the GIA Laboratory. As an example, to qualify for an Excellent cut grade in the GIA Diamond Cut Grading System, a diamond’s girdle thickness needs to be between Thin (THN) and Slightly Thick (STK).
