No. Though, it's not only the rarity of presence that matters but the aesthetics of appeal to those who value such.
No, because they are not.
I'm a geologist, so no, I would not be surprised.
Yes they do.
Not particularly. It's more likely to be something I've never heard of...
Ruby's just corundum, isn't it?
Learning that diamonds were worthless was one of the bigger steps in me questioning all of society's norms.
No. Everyone seems to have diamonds.