Polish measures the quality of finish on the diamond facets. Like streaks that remain on a car after waxing, polishing lines can also remain on the surface caused by polishing wheel after diamond cutting process and reduce the amount of light that enters the diamond. A considerable amount of time is needed to properly polish a diamond and sometimes this is reduced to cut labour costs. Depending on the amount of polish lines and the visibility of these under the naked eye or a 10X magnification, the diamond polish is graded as follows:

• EX or E – Excellent,  Flawless at 10 power
• VG or VGD – Very Good, Extremely difficult to locate under 10 power
• GD, GO, G – Good, Very difficult to see under 10 power
• F, FR, FA -  Fair, Noticeable under 10 power
• PR, PO, P -  Poor, Easy to see under 10X / Visible to unaided eye
• VP, VE, -  Very Poor, Relatively easy to see with the unaided eye
• EX or EP -  Extremely Poor, Obvious to see with unaided eye