I agree with Dngnkeeper on this one. It's really up to the couple.

Nathaniel, my pet, wears a collar for me in private. He looks pretty adorable with the leash between his lips. Having him in a collar was and continues to be a big deal for us. We had a very nice ceremony for the first time he put it on. If we ever decide to go to an event as a couple, you bet he'll be wearing his collar. He's mine, all mine!

Yes, as blu confirmed, the domme part of me wants him marked as very taken.

My husband, T, has a ring on my finger and I have one on him. The collar isn't as important to T. Yet we recently went to an anime convention and I dressed as a furry, wearing one of my play collars. He got this nice big gleam in his eye when I put it on and that made my day.