Bottom Line Recommendation:
Diamond Polish refers to how smooth the outside surface of a diamond has been polished. You can achieve higher grades by using a finer grain diamond dust on the polishing wheel and polishing for a longer time.
I have worked in the industry for over 6 years, working for one of the largest and most well respected firms with offices in over 10 cities all over the world, and I cannot distinguish between an “Excellent” Polish diamond, a “Very Good” Polish diamond, or even a “Good” Polish diamond. Technically speaking, “Excellent” Polish diamonds have been polished longer on the polishing wheel with a finer grain of diamond dust, but the simple fact is, if I can’t tell the difference with a 10x loupe, there is absolutely no way you will ever be able to perceive a difference without it.
So while it might look nice on a piece of paper to have a pretty word like “Excellent” written three times, it’s certainly not worth the extra 10-20% you’re going to pay for it. It would be like a car salesmen convincing you to purchase a $5000 upgrade package for a “friendlier cabin aura.”
If you have any questions, please post them in the comments below. I will usually respond within 24 hours.