People have known this for a generation though... it's a purely marketing-manufactured 'tradition.' However, diamonds continue to sell.
If I were ever going to get married, which I doubt I will, and I were going to buy a diamond ring for the broad, I'd get a decent diamond with the little certificate of authenticity that comes with it. Then I'd buy a synthetic diamond of the exact same weight, cut, color, etc. I'd give her the replica and the certificate of authenticity, and I'd keep the real one in a safe-deposit box somewhere. If there's ever a divorce she gets the fake one and I walk away with the real one. I get it appraised and sell it, and when she tries to sell hers they tell her it's a fake. If there's no divorce, she never needs to know. If she tries to "sue" me after finding out it was fake I just say "OMG we were ripped off by the diamond merchant, so sad."
