Polish influences how well light is able to pass through a diamond and is very important to a diamond's brilliance. It is necessary to select a diamond that is laboratory certified with good, very good or excellent polish. Diamonds that have poor to extremely poor polish are less brilliant because they have microscopic polish lines that blur the surface of the diamond. These polish lines reduce the amount of light that enters or exits a diamond. When selecting your diamond be aware many diamonds possess poor polish. Diamond cutters can greatly reduce labor costs by not taking time to properly polish a diamond.

• 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