Of all the 4 Cs, cut has the greatest effect on a diamond’s beauty. The diamond grading process is evaluated by the cutters skill in the fashioning of the diamond based on the cut.
So when you’re looking for your engagement ring, make sure you confirm the cut of the diamond. Be cautious when comparing stones using different grading systems.
For instance, GIA’s (Gemological Institute of America) highest cut grade is “excellent”.
AGS’s (Accurate Gemological Laboratories) highest grade is “ideal”, while the second highest grade is “excellent.” This can create confusion.
When jewelers talk about the cut of a diamond we are referring to its proportions. When a diamond is cut to good proportions, light is reflected from one facet to another and then dispersed through the top of the stone. However, when a diamond is cut too shallow or too deep, the internal reflected light leaks out from the bottom of the stone, diminishing the brilliance of the stone.