loughnane is right. What you send in to the anodizer is what you get back. If you send them a part that has mill marks, you will get back a part with mill marks. Actually, the process tends to highlight flaws in the surface. It will also slightly dull the existing finish. The Apple finish appears to be type II (sulphuric acid anodizing) class 1 (non dyed.) The metal will be bead blasted to a finish that is slightly shinier than the desired finish before anodizing.
Typically, the anodization process works best on machined aluminum (6061 is best) , it is much harder to get a good anodized finish from cast aluminum. I don’t have any experience with it, but I think this holds true for extruded aluminum as well. So if your part is going to be stamped from an extruded sheet of aluminum, I would speak with the finishing shop to maker sure there won’t be any problems.