So don't buy one. My girlfriend's will be getting one of those rings made of tungsten. Have you seen them they look amazing. It's simultaneously looks like something some elvish jewellery merchant made while at the same time looking like it made also activate the halo rings.

A diamond is just shiny.

Of course it's important to discuss these things with your partner in advance. Whether or not they would be happy with a non-diamond ring depends very much on the person. But it might be worth advocating for them because they look really nice and they are quite expensive but they're honestly more interesting than the diamond and ethically sourced. There's no such thing as blood tungsten.