Diamonds have become so generic (or maybe they always were). It's like gold. People just buy gold because it's gold. Personally, I hate the typical red gold and I absolutely love silver, iron, steel, titanium, tungsten and platinum. I can understand someone wanting an absolutely huge diamond, though. One that is actually rare. I dunno about wearing such a monstrosity, however; we're talking large here.
It's really nice when people wear jewelry that's right for them, like emeralds or something like that. It then becomes something personal and as a gift it's more personal too. Diamond and gold are the black of jewelry, anyone can wear it, but because everyone does wear it, it says nothing about the person and is just there, hanging like a pricetag off your ear or whatever. It is almost painful giving and receiving diamonds. Because they are so "generic" it becomes a matter of counting them, the carats, and adding it up. It's not a far stretch from giving cash. Of course, there are exceptions, designs that make it special...but...nah...
There is one thing that is absolutely 100% "Verboten!!!" and that is a jewel encrusted wrist watch. My god, those look so awful. I don't care how much they cost and that some people actually find them "brilliant". It's the neutron star equivalent of Liberace. Super-condensed glittering evil. "Get it away from me!!"