It’s sparkly, it’s clear or it’s colored, it’s cut in more ways than one person could dream up, it sits on your finger like a golf ball or a just-the-right-size bauble, it’s a girl’s best friend — twinkling alongside many a wedding proposal has been a diamond. And a lot of the time, these chunks of bling cost a pretty penny. So why do we do have this shiny ritual? (And someone please explain how a diamond can be a best friend? It can’t even talk.) [More]