I don’t think that liking a diamond ring in and of itself is wrong or has anything to do with being a feminist.
But then you may have to delve into the definition of feminism. For example, to me, feminism is also standing up for human rights and speaking up against oppression. So the idea of liking a diamond ring sickens me because of the abuse and suffering that comes with this industry.
It’s the same reason why I try not to eat meat unless I know where it’s come from even though I’m not vegan. I kinda feel like I’m betraying my fellow women by saying it’s OK for me to enjoy wearing a big diamond knowing what some women (and men) had to go through to bring that stone to me. And for what? How can I call myself a feminist if I do not stand up against the industry that so brazenly abuses fellow women’s rights? Or just plain human rights for that matter. Every time I look at a big diamond ring I can’t help but wonder how many people had to go through utter shit to bring that stone to the West and find its way to the wearer’s fingers.
It’s not diamond per se that has anything to do with being a feminist, it’s the industry that goes against everything feminism stands for (for me at least, because of my definition of feminism to me).
Anyway, just food for thought.