The GIA Diamond Cut Grading System assigns one of these five grades to describe the overall cut quality of a standard round brilliant diamond in the GIA D-to-Z color range, and the Flawless-to-I₃ clarity range. Each cut grade represents a range of proportion sets and diamond appearances, each of which may conform in different ways to the characteristics of that grade.

We have concluded that there are many different proportion sets that provide top-grade diamonds, and even wider ranges of proportions that are capable of providing pleasing upper-middle to middle-grade diamonds.

And while it is important to consider many components when assessing the overall cut appearance and quality of round brilliant diamonds, an individual's personal preferences also play a role. The GIA Cut Grading System provides an objective assessment of a diamond's overall cut quality. Because each cut grade represents a wide range of proportion sets, the system also gives individuals the freedom to choose which particular appearance they prefer.

With GIA's new system, the diamond industry as well as the public can now use cut along with color, clarity, and carat weight to help them make informed and balanced decisions when assessing and purchasing round brilliant diamonds.