Congratulations!
My husband and I met due to our mutual bladesmithing habit so we of course wanted to forge our own rings. We loved the idea of it being real blade steel, two bladesmiths welded together into one. We thought we'd give it a try and see how they fared. They do darken and brighten depending on how much wear they are getting. We need to try a bake on laquer maybe? They also rust every so often, like if you have your hands in wet gloves for a long time.
It's been over a year that we've been wearing them and we haven't upgraded yet but I would certainly recommend some sort of coating if you go with carbon. We forged a special twist billet together and flattened it in the press to get the pattern to show right. We just drilled two holes and cut them out and free hand shaped them on the grinder. He made mine and I made his. We hardened them so they would etch properly.
Good luck on your quest, I've seen some lovely stainless rings online. I've personal had a stainless (non damascus) ring and it fared just fine with no corrosion in some of the worst conditions in and out of salt water. Rings get enough normal wear to keep 'em clean. Precious metals on the other hand wear thin over the years if you do alot of work with your hands which is why I had traded in my silver ring for a stainless.
It's such a personal choice, go with what you two love and do whatever upkeep you need to keep it pretty!
-HD