Rolex Geneve Cellini

[ANZYANZ]

I've just come across this Geneve I like the look of but wondering what's going on around the back. It almost looks as though it's been ground down ... anyone out there that can tell me more?

From the Hallmark inside the caseback it's a 14K 1959 Birmingham ref 00187 with a 1600 Cal inside. I've asked for confirmation of any hallmarks on the case itself as there aren't any showing on the lugs.