The sporran is indeed black. It's the only one I own at the moment and I'm not too concerned about clashing with non black leathers since I only wear brown shoes casually and the burgundy shoes in the photo with smart day-wear. I don't wear a day-wear belt so I won't clash with that, and it would probably be the item I was most worried about as the belt and sporran are right next to each other.

Indeed, I only wear my brown hose with black shoes because I prefer a small amount of contrast. For day wear I think black and brown leathers are fairly neutral and go along equally well with the earth tones common in highland dress (with the exception of many tartans, though I find the contrast really shows off the tartan better).