If you don't already know about the hoax that is diamonds, a good starting piece of education is Edward Jay Epstein's work. Gem diamonds are not rare or valuable for industrial purposes, and the company that keeps the price artificially high (DeBeers) has been prohibited from doing business in the U.S. under anti-trust laws for decades. The fact that the people who actually do the mining make no money and the fact that "blood diamonds" are used to fund wars in poorer parts of the world only makes the whole situation worse.

So, it's nice to see companies providing alternative sources. Through a process called "chemical vapor deposition," diamonds can be produced of a size and quality almost impossible to find in nature. The price per carat is around $5. (original link to blog here from Teeg).