This is true, they are different. but "fine" or high polishing and rust blue don't really go together. Rust blue does in fact slightly etch the surface some and this is what gives it that very slight matte and very fine little "sparkle" in the metal. There is really no reason to polish any higher than a 320 finish for rust blue because the etch that takes place will set {in a manner of speaking} the final surface finish anyway. Also, more than a 320 finish and rust blue has a hard time getting "started". You really don't want a high ultra gloss chrome looking flawless Rolex polish on metal to be rust blued.
It also doesn't sound like rust blue is what the OP is looking for...rust blue has a slightly lighter blue "frosty" look to it. What he described is a very high polish and Oxynate #7
Edit: I have tried multiple times to upload a few photos of rust blued Parker DHE barrels and a 1911 "civilian" with high polish...but I keep getting a stupid "ERROR, server cant handle it" message. Anyone else having this issue????
Can you tell us more about this oxynate #7? But yes Im looking for that black mirror look.