The finish of a diamond consists of 2 important attributes, which are the Symmetry and the Polish. The polish and shine of the diamond are called by the manufacturing process of the diamond. Once the diamond has been cut and faceted, it is often polished so as to help it shine and bring about a smooth finish.
If the polish is not done well, the sparkle of the diamond can be severely affected. Take the polish to the final layer of varnish on a piece of wood, that makes the wood shine and glisten. In the case of diamonds, the lack of a shine can impede light from entering the diamond and cause its brilliance to drop a notch
The diamond is examined by a gemologist at 10x magnification so as to determine the ‘polish grade’.
The Polish Grade
The grade of the polish tells you how well the polish is performed and how little it has affected the brilliance and sparkle of the diamond. The polish grades are done based on the visibility of the polish lines and the blemishes, if at all, on the skin or surface of the diamond.
The Polish grades are as follows:
Excellent: This is characterized by a lack of visible polish lines or any other blemishes at 10X magnification. Light is able to enter the diamond and exit, without any hindrance to its path. All of this goes to form a beautiful cut diamond specimen.
Very Good: These have minor polish lines and blemishes that are visible at a magnification of10X. The polish lines have little to no impact on the incoming light and the diamond’s sparkle. This is a diamond that can earn an Excellent Cut grade.
Good: These are characterized by visible polish lines and inflections on the skin of the diamond when viewed under a 10X magnification. The diamond’s sparkle takes a beating as the light is unable to penetrate the skin of the diamond well. This is a diamond that can earn a very Good Cut grade.
Fair & Poor: This is the polish grade that you mustn’t go for. This has noticeable finishing errors in the form of the polish lines. These blemishes impact light performance negatively and reduce the diamond’s ability to sparkle well. If you have the choice, choose to not go with this polish grade.
With this information in mind, you can better choose your diamond ring. You can get details pertaining to the polish grade of the diamond from the GIA certification that comes along with the piece.