The word glaze gets used in a lot of ways. Sometimes it means oily filler, sometimes it means polymer finish but can mean just about everything in between. So, the answer is yes, a glaze can mute the shine but a good glaze shouldn't. (No matter what the glaze really is.)
When it comes to metallics I find polishing to the highest level reveals more color and more of the shine from the individual flakes. Sometimes, if the car has a light layer of oxidation and some scratching, polishing makes the metallic so much more visible the clients are surprised how much metallic their paint has.
The way I see it is this: The paint should be polished to the point where it looks finished before anything, any wax, glaze, coating, polymer, etc. is put on. The paint should look like it would have if it had been applied then never touched - what some people call - gun shine. After that you need to find a good protectant that doesn't detract from the finish you've achieved.
It's a lot easier to go backwards than forwards at the top levels.
Robert
