Why is it diamonds, and not iridium, pearl, or opal? Why does a diamond's value depreciate to nothing the instant it's sold, unlike gold? Why did the price of diamonds shoot up so drastically in the early 1900s? Why are the indistinguishable lab-grown diamonds in so much lower demand? Who are the major actors in the diamond trade, and what are their strategies and relationships to one another?
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)".
Seriously? Economics 101: supply and demand. Or is this a rhetorical question, with some kind of social justice slant?