Diamond Image Gallery Desirey Minkoh /AFP/Getty Images

      Few things elicit the response to the gift of a clear, perfect diamond -- particularly if given in that trademark Tiffany-blue box. Women clamor for them and men shell out thousands of dollars for engagement rings, pendants and the like. Friends compete to see who has the biggest and best diamond ring, only to be one-upped by the next friend to get engaged (if her fiancé knows what's good for ­him).

      This phenomenon has its roots in marketing by the diamond industry -- ruled largely by the company De Beers -- and has reaped benefits for decades. In 2005, the diamond industry was estimated to be worth a whopping $60 billion [source: Blood Diamond Action]. Diamonds are judged on the Four Cs -- clarity, color, cut and carat weight. Read more...