https://www.theatlantic.com/international/archive/2015/02/ho...
So arguably buying a diamond ring has always been a symbol of wage oppression and terrible mining conditions in Africa, and any right thinking person should boycott it.
Fortunately my SO isn't that struck by sparkly rocks. She prefers antique jewellery with character and history. Her wedding ring is 150 years old.
The growth in diamond mine production in the late 1800s tremendously increased diamond supply. DeBeers took advantage of historical perception of rarity and actual lower cost of materials to create a new market.
https://en.wikipedia.org/wiki/Medieval_jewelry
Although to be fair, this was in part because diamonds are hard to cut and they don't look good without faceted cuts. Diamonds only started becoming popular in the late 1800s when South African mines started producing them in bulk and modern cuts were developed, and they went mainstream once the De Beers marketing engine kicked in after WW2.
(Added twist: the jeweller couldn't have it ready in time for the ceremony, so we made do with a dime-store trinket, and swapped it later.)
It's also nice to think that the ring has had a life of its own already and you get to be another chapter in it.