Diamond finishing consists of two factors: Diamond Symmetry and Polish. A diamond’s polish is the result of the final process in manufacture. Polish give the diamond its shine and smooth ness which allows the light to reflect and refract. Polish can affect the diamond’s sparkle if not done well.
Following are the grades of Polish:
Like symmetry and every other attribute, polish of a diamond is also graded by GIA. The grades are based on the visual detection and visibility of polish lines or other blemishes on the surfaces of the diamond. These are checked by gemmologist under 10X magnification.
Excellent:These are perfect diamond without visible polish line and blemishes.
Very Good: There can be very slight and minute polish details visible under 10x magnification. They have negligible impact on the appearance of the diamond.
Good: These grade diamonds have certain visible polish lines or blemishes but are only visible under 10X magnification. Appearance and sparkle might get affected.
Fair & Poor: There are noticeable deformities in polish lines or blemishes and have an impact on the appearance. These blemishes might hinder the visibility and sparkle of the diamond.