It's definitely not just that, because placing huge import on diamonds, and gushing over their (much agreed upon) beauty, and having preferences for stones and cuts etc., and showing them off at the office, and talking about their size and how much they must have cost, and equating some of those things with the size of someone's affection and worth as a person, are still ubiquitous in (at least) American society.

As far as I can tell they're only on the way out with bleeding-edge progressives.