It looks like the clasp snaps on the back side of the cover when you close it. I actually prefer the snap closure on the front, but a lot of them are made that way now (with the closure on the back).
I've not had any discoloration problems, but the ones I have are pink and white, so no dark colors. Don't know about the black.
This is the one I got:
http://cgi.ebay.com/Amazon-Kindle-DX...item27ba3d480e