The answer to all these questions is the same.
Only if that answer is "the world is incredibly complicated and each individual situation is laden with its own history, nuance, and complications." Because otherwise: no, the answer to all those questions is very different, because the world is incredibly complicated and each individual situation is laden with its own history, nuance, and complications. It's reasonable to ask about what those particular nuances are for a given situation without being brushed off like this.
Mercury could have an 11-mile underground layer of diamonds, researchers say | CNN
https://www.cnn.com/2024/07/31/science/mercury-diamond-under...
Seriously? Economics 101: supply and demand. Or is this a rhetorical question, with some kind of social justice slant?
Many books could be (and, I'm sure, have been) written on these subjects. Don't act like "Econ 101" explains everything. "Econ 101" introduces a bunch of extremely simplified models that are later qualified, criticized, complexified, or even outright replaced. That's all fine if you're continuing on to get your economics degree, but I'd argue that someone who took Econ 101 without continuing into much more depths in economics probably has a worse understanding of the world than someone who never took it, because they take these ridiculously over-simplified models as some sort of inalienable truth. After Econ 101 you merely "know enough to be dangerous(ly wrong)".
Ordinary diamonds, perhaps. For large/rare diamonds like this one, the value would go up with time.