GIA 6223267102 diamond’s table 57%, crown angle 36.5, and pavilion angle 40.6, it‘s a 3EX diamond，but in “cut estimator”, this diamond not sit in GIA Excellent range, WHY?
The cut estimator shows GIA’s proportion-based cut grading criteria. GIA has many more measurements (with more precision) than table, crown angle, and pavilion angle when assigning their cut grade in-house. The cut estimator is the best you can do in the absence of GIA’s in-house data, but you should rely on their official grade.
That said, in my computer vision analysis, the 36.5/40.6 combination typically shows nice optical symmetry. So even though it doesn’t technically fit the GIA and AGS proportion-based cut grade criteria, based on actual appearances they often appear as ideal in my price curves. And you can see that in the visual examples shown in the cut estimator.