Because with a universe as big as ours, some things like diamonds are valuable here because they are scarce. But somwhere else.... maybe not so much. Have to love how big of a universe, with so many galaxies and stars, even the rarest of things can be plentiful; hopefully the religous one day can respect statistics in numbers and long durations of time.
http://www.sciencedaily.com/releases/2012/10/121011090647.htm
Diamonds are actually not all that rare on Earth. The reason they're so expensive is that one company, DeBeers, essentially has a global monopoly on them, and it has successfully foisted a variety of ideas on various societies, such as the notion that an engagement ring has to have a diamond in it, and that diamond has to be a certain size, and so on.
Diamonds are very commonly used in drill bits because of their hardness, and if you do a Google shopping search on diamond drill bits, you'll see that they're not very expensive. Although, admittedly, the diamonds used for drill bits are not gem-quality diamonds.
An interesting article, in any event, though. The planets that are being discovered are a lot stranger than I would have expected -- such as this one having a year that's only eighteen hours long. Very surprising.
