The challenge is that so many of the natural diamonds for sale are of such poor quality that they are not that attractive. They are also extremely overpriced.
For young people with limited budgets, buying an overly expensive diamond ring does not seem like a good financial decision. There is also a big push to ensure responsible sourcing and no harm to environments.
However, I constantly see famous celebrity women getting engaged and flashing monstrous stones, so the wealthy are still making serious diamond purchases.
Perhaps buying man-made diamonds is a substitute, but those gems have limited resale value and also too high priced in my opinion.
I like going to antiques shows and looking at old diamond jewelry. Maybe one of these days I will splurge on a big stone, since it is also my birthstone. I do appreciate all of the smaller diamond jewelry pieces I have collected over the decades, but my purchases are very limited now.