It’s not only that. Lab diamonds are superior in every way I’ve heard of. The emotional appeal of their provenance is the sole remaining reason I’ve heard people claim that slave diamonds are superior. I contend that they’re worse there, too. In fact, the only reason I can imagine someone preferring mined diamonds is that they genuinely value the human suffering that goes into them.
If you ignore the ethical issues, and you shouldn't (!!!), there is an appeal to mined diamonds, and it is exactly what you say above. The idea that some dinosaur or tree or whatever got mushed down is really interesting too.
I think it's more ignorance, only sometimes willful, than actually enjoying human suffering. Then again, voluntary human suffering is part of the story that sells art, so there might be some of that in there too.
