I did propose with a diamond ring, for which I paid a substantial portion of my income, but since I was in grad school at the time, my income was very modest.
The next time you look at a diamond, consider this. Nearly every American marriage begins with a diamond because a bunch of rich white men in the 1940s convinced everyone that its size determines your self worth. They created this convention – that unless a man purchases (an intrinsically useless) diamond, his life is a failure – while sitting in a room, racking their brains on how to sell diamonds that no one wanted.
With this insight, they began marketing diamonds as a symbol of status and love. —Priceonomics Blog