I gave my wife a natural diamond engagement ring, but it belonged to my great-grandmother, so I felt that it was ethical enough. You can’t really do much about suffering 120 years ago (or whatever it was) and probably everyone involved in making that ring was treated like shit in one way or another because it was 1904 and everyone who wasn’t white, male and rich suffered.
The most suffering-free and eco-friendly ring is the one already made, so, you did the best thing!
How many world wars were fought in the last century? The answer might surprise you!
If by last century, you mean 1900-1999; 2
If you mean in the last 100 years; 1. Which is honestly impressive all things considered.