When my wife and I were discussing getting married, we agreed that a diamond was a waste of money. That was at a time when most diamonds were coming out of apartheid South Africa, so we also had an ethical issue with buying one. After several years of marriage, she decided that she wanted a ring after all, so she picked out a nice CZ ring for a couple of hundred dollars.
If you think a diamond is forever, it isn’t. My mother’s diamond was shattered internally when a window sash fell on it. B”H, her finger was fine.