Even if there was an answer to your question it may not be useful.
I've bought several diamonds and can never find out anything about their provenance, history, origin, past, let alone what country they were mined in.
Most vendors are very hush hush.
You get the diamond, a grading report, sometimes an "appraisal", and that's it.
There are companies marketing diamonds known to be mined in Canada, but not in South Africa, AFAIK.
depends....
Some of the largest highest quality rough has come out of Africa.
So has tons of very poor grade rough.
Many of the mines in Africa are old and long worked and the average rough quality goes down as a mine gets older and deeper.
On average probably the cleanest rough is probably coming out of Canada these days.
What the rough is counts far more than where it came from when it gets polished into a finished diamond.
Argyle pink diamonds from Australia trade at a huge premium. They're different because the extinct volcano they live in is fundamentally different from every other extinct volcano diamond mine in the world.
Pinks are insanely rare anyhow, and a nice pink from anywhere is going to trade at a high price. But I'd bet it would have been a higher high price if it had had the magic Argyle tag on it.