http://www.badgeranodising.co.uk/colour.shtml I have not used these people in Birmingham, but did speak to them about something I was thinking of doing in the past, they seemed very reasonable and helpfull.
Quoted by Phil
Remember with all special finishes - if its not super shiny to start with - they will look worse.
Any kind of finish, whether it is anodised or plated, highlights all the flaws and imperfection of the base surface they are applied to.