If some doesn't like the colourof your mount Ralph they can still add a black over-mat

The issue of frames arises when a mounted image has to be put in a galleries set of frames, they may be a different standard, Centimetre rather than Inch, or vice versa, but with photography it's rare that galleries use anything other than white mounts. I prefer to do the matting change myself, but it doesn't happen very often luckily.