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.
Seriously? Economics 101: supply and demand. Or is this a rhetorical question, with some kind of social justice slant?