Big example of real rituals which have purpose, Key Signing Ceremonies. Small example, when I leave somewhere I always pat both pockets twice, everything I absolutely need is always in those pockets, keys, wallet, phone. And so I won't leave them behind.
The weird thing about the diamond engagement ring is that it isn't a powerful symbol of anything. The wedding ring is the powerful symbol, and that would conventionally just be a metal band. You see those everywhere which is of course made more practical by their being a simple metal band.
After my wallet fell out of my pants pocket into my office chair and I thought I'd lost it for 2 days, I updated this ritual to do it every time I walk through a doorway. That way if I lose something I know exactly which room it's in.
Was just about to post this. I didn't start doing this on purpose, but at some point I noticed I was.
https://www.scientificamerican.com/article/why-rituals-work/