The world of famous gemstones is a strange one. If we had a nickel for every gargantuan, mystery-shrouded, supposedly cursed ruby or diamond, we'd have … well, enough money to buy one of them. And then we'd name it after ourselves, of course. Expensive gemstones tend to disappear with unknown owners, resurface at auction years later -- and then sell to an anonymous buyer and disappear again. So, it's pretty difficult to nail down values for them. But give it a shot: How much do you think these gemstones cost?