Ok, so I was a little suspicious of the fact that there seemed to be contradictory rules regarding this whole color issue, and as the information presented came from "a pamphlet issued by Lord Lyon" that had been "reproduced on electric scotland," I thought I'd go right to the source and look for information on the Lord Lyon's own web site.

About the crest, as it should be displayed by clansmen:
It is correct for these people to wear their Chiefs Crest encircled with a strap and buckle bearing their Chief s Motto or Slogan. The strap and buckle is the sign of the clansman, and he demonstrates his membership of his Chiefs Clan by wearing his Chiefs Crest within it.
Note, no mention of color at all, one way or another. Granted, the information on the web site is pretty basic, and no doubt there is more thorough information available from them upon request.

The only mention I was able to find about the color of the belt specifically was in the guidelines for the Pinsel, which is the heraldic banner flown by a representative of the chief, when the chief is not present, and this is to show his crest within a belt of the "second livery color and buckle (Gold for full cheifs)."