It was Leonardo DiCaprio who played a diamond smuggler in the movie Blood Diamond, a 2006 thriller about the violent diamond trade during the Sierra Leone civil war. Now the actor is investing in a startup called Diamond Foundry, which says it can grow real diamonds in just a matter of weeks. The company might be able to create an alternative to draw business away from the brutal conflicts that make diamond warlords rich. How do you grow diamonds? Apparently, they can be created in chemical reactors, using just a sliver of natural, mined diamond, which then grows layer by layer from a superheated plasma. The company has been doing research into growing diamonds for the past two years and is now almost ready to start production.