At the Gemological Institute of America (GIA), the grading system for cut heavily depends on the craftsmanship of the diamond cutter. One of the most important elements is the polish given to the diamond.
"Polish" refers to the quality of the diamond’s surface regarding the polishing process, blemishes, and wear and tear. Blemishes are only on the surface and do not affect the inside of the diamond.
Polish is graded as Excellent, Very Good, Good, Fair, and Poor. As with the rest of the diamond grading process, assessments are made independently by several individual gemologists to prevent bias and a consensus is derived from their results. At 10x magnification, the diamond is assessed one section at a time in different positions, but emphasis is placed on the face-up position of the diamond.
Polish is a part of cut, but on a diamond grading report (GIA or AGS), polish and symmetry are listed as their own categories.
Polish is one of the factors affecting a diamond’s grade, and therefore the value of a diamond, just like clarity, color, or carat. Do not settle for a low grade; it is no use having a perfect diamond if the polish prevents the diamond from sparkling to its full potential. Polish is a part of the cut grade, is also a decisive factor to whether a diamond is Triple Excellent or Super Ideal.