I, um, used acid on some granite steps

Well, not exactly. I used some (very diluted, I thought) muriatic acid on the cement at the top of my balcony to get rid of some very ugly brown stains, and (http://maplered.com) it worked OK (it changed color from a nearly white grey to a rather pleasing beige; I was a bit surprised, but it actually looks better than before). Anyway, the problem is that the acid eventually dripped on the balcony's grey Granite (http://tanbrown.org) steps. They still look fine, for the most part, but some parts of the first two steps (near the rise and (http://maplered.com) at the edge) have changed color to a very dark grey-brown.

Have I permanently damaged my Granite (http://tanbrown.org) steps? Is there any way I can fix this (or at least, make it look a bit better)?


Thank you very much.