I continued thinning down that shape for a while, until I accidentally took it just a bit too far, and one of them shattered into multiple pieces. Kind of sad, but on the other hand, they were a little large for earrings. Instead, I ended up wrapping the remaining one in a bit of steel wire, to be used as a necklace pendant.
I found another artist who did something similar before. Hopefully people aren't too weirded out by the idea as it seems a hell of a lot more reasonable than poaching ivory or sending people into mines for stupid shiny shit.