i've not seen this (or the other bags in the rebelle line) in real life yet, but from what i can tell, the colour is the same metallic silver tone used in the gaucho. (and the colour does look very lovely)
if i remember correctly, there are pictures of the rebelle hobo somewhere, i think it was Jill who bought a green one and posted pictures of it.
http://forum.purseblog.com/dior/jill-finally-bought-the-rebelle-bag-lol-29604.html
(pictures are right on page 1 itself)
and here are the pictures she posted up for the tan and chocolate brown rebelles:
http://forum.purseblog.com/dior/omg-dior-sa-sent-me-these-pics-choc-38492.html
i hope that would be of some help in aiding your decision.
i'll probably be headed down to the dior in manchester sometime next week, so if i see the rebelle, i'll take a look and hopefully give you some feedback about it.