On the topic of engagement rings: I asked my wife-to-be if she wanted one. She said “how much do such things cost?” and I told her what I was thinking of (that is, the money I’d set aside for that purpose). She said “which would you rather do with that money - give a ring, or go on a really nice adventure trip together?”. So, no fancy ring. Instead, we spent some months in Indonesia, Malaysia and Thailand. I never regretted that decision, and neither I think did she.
That was many years ago. I just gave my wife a ring to mark the 20th anniversary of going out together. Not terribly expensive, but nice and sparkly with diamonds - I figgured that they looked nice. I wasn’t originally going to get diamonds because they are said to be over-priced, but what the heck? They really do look nice and sparkly, and we’ll never (hopefully) be in a position where we have to sell it.
To my mind, a ring and gems are luxury consumption - pure and simple; we never got fancy jewelry before, because we prefer other luxuries. But I’m the last to condemn someone elses’ choices in these matters.