It’s always the same on any thread about proposals. People come on and say, “Oh my DH just lobbed a Haribo at me and shouted, “Oi, book the registry.”
I remember one woman on here who seemed genuinely delighted to reveal how her DH proposed to her while she was on the toilet 
Meanwhile, in the real world, most men do actually propose in a reasonably normal fashion.
No, the length of the marriage will not be determined by the proposal situation, but some women seem to be under the delusion that a crap, thoughtless proposal is actually preferable or more genuine Their main evidence for this seems to be the fact they’ve so far steered clear of divorce.
If someone proposed to me while I was on the loo, I would have been livid. That would be it.
I’m no princess and I’m not one to stand in ceremony in general, but my view is, if a man wants to marry you, the very least he can do is make the effort to ask you in a meaningful way. I mean, it’s not that hard is it? Buy a ring; create a moment; ask a question? It’s not rocket science. Call me old-fashioned, but that’s me and there it is.
When DH proposed to me I really wasn’t expecting it and I had no fixed ideas about how it should pan out, but now I’m older (18 years older), I really appreciate the fact he thought about it and tried to make it special because these moments stay with you. We were on some cliffs over the sea in my home country and we sat on a bench to see the view, but he got on one knee and said some lovely things which so still remember and the thing is, when you have moments like that (any moments) it helps you get through the rough times. The ring he gave me was a platinum diamond solitaire, but he wouldn’t have minded if I’d wanted to change it (I didn’t as so don’t really wear gold).
He later admitted he’d been super nervous about proposing for weeks. OP, I think this might have also been the case with your DH. Maybe the nerves just overwhelmed him a bit in the moment? I think your ring sounds lovely. I’m sure he wouldn’t mind if you told him you wanted gold though. He probably just wants to make you happy.
The main thing, I always think, is not the actual actions themselves, but the intention behind the action (if that makes sense)? He hasn’t just proposed on a whim. He’s tried to get you a ring he thought you’d like based on a comment you made about your friend’s ring. And at least he actually went to the trouble of formally asking you which, if we are to go by MN, is a great hardship men shouldn’t have to put themselves out to do these days. No, we should either ask them ourselves, or just be happy with a quick business-like mention of the subject and preferably no ring, no party. Nothing.
So, in the parallel world that is MN, your partner is streets ahead already 
Try looking at it this way. Change the ring if you need to. Congratulations!