I made a man's engagement ring (on the left after the link) for a client in April of 2008, and when we sat down to design his wedding band we wanted to make something interesting that complimented the original without overshadowing it. Because of the nature of how I'd scalloped out the negative space of the wax model for the ring, we decided that a hammered surface would emulate that nicely. He also chose rose gold to make it stand out against the silver surface of the engagement ring when he wears them stacked.
In an unusual turn, he and his bride actually came to my studio to personalize the ring by helping to hammer some of the dents into the surface. I love the interplay of the reflected light from the contrast between the smooth sides of the ring and the hammered outer surface.