A highly polished surface will produce a shiny blue, if you were to bead/sand blast something before bluing the finish would be dull, also depends on what you use as the Browning solution, (this is what is applied to produce the rust) some with acid in them which will etch the prepped surface, if you ever want to do home Browning or bluing all you need is a salt solution, its that simple....... the item in question needs to be spotless clean , apply the solution and leave in a warm area or leave outside, once rusted ( this all depends on the solution and what you want to achieve etc, (the reason its called controlled rusting) boil in distilled water for 20-30 mins, you will have to repeat the process up to 5 times but a dark dull blue/black, can achieved using this.
For anyone interested I've a few small items from a Mauser Stock I'm bluing shortly........... I can go over the process in the restorers corner etc.