Some time back DeBeers was trying to prop up the price of diamond with their "registered natural diamonds" campaign. These"registered" diamonds had a micro number engraved via laser on them, visible only by microscope. I immediately wondered why this would be necessary if the natural diamonds were provably better than man-made. The answer of course is that man-made are no different, except that they tend to have LESS flaws than natural. Immediately exploding the "rare and exceptional" diamond sales model.