Polish Grade Guide

Polish grade rates how smooth the surface of each facet is after the stone has been cut. At Excellent, polish lines are invisible even at 10 times magnification and the stone returns light without any surface-level dullness. At Good or Fair, polish lines can slightly dim the brilliance, most noticeable in strong directional lighting. Polish is one of the three grades (along with symmetry and cut) that together form the Triple Excellent designation that premium retailers use as a quality shorthand.

The premium for Excellent polish over Very Good is tiny, usually a few percent, because most cutters produce Very Good or better as a minimum standard. GIA grades the vast majority of modern stones as Excellent or Very Good on polish, and the price difference between the top two grades on a GIA report is small enough that Excellent is almost always worth the upgrade. Where polish matters most is at the lower end: a Good polish grade suggests the cutter compromised on the final finishing, which often correlates with a less carefully cut stone overall.

Always insist on Very Good or better polish. Excellent is cheap at the top, so pay the small premium. Skip Good or Fair polish outright; the saving is trivial and the reduced brilliance is not worth it.