Diamond Polish is also graded like symmetry with what appear to be vague adjectives but are in fact precise qualitiy tags:

Ex = Excellent, ID = Ideal [Different terms use by different labs. they are the same quality]
VG = Very Good
G = Good
F = Fair
P = Poor

These quality codes define the finished surface of the diamonds facets. A diamond can have different textures and direction of the carbon composition. This means that when polishing a diamonds facets different directional movement and various degrees of coarseness will give a better finish or polish. Diamond polish can be compared to sanding wood, cutting meat or painting; there is a general direction and texture to be observed for excellence. An excellent or very good polish will perform better than a good polish and a fair or poor polish could have noticeable blemish marks and should be avoided. General value and performance can be found with Good to Very Good polish with Excellent/Ideal polish a premium for the best finish.