I have been planning to buy one for myself, although it wouldn't happen in the near future, I don't really expect a guy to buy one for me. Diamonds are a girl's best friend and a man's worst enemy, if that's the case, then girls really don't need guys to buy it for them.
The world's most expensive diamond item is the diamond bikini by Susan Rosen and Steinmetz amounting to $30 million while Sotheby's white diamond amounting to $23 million ranks #2 but the most expensive diamond of them all is the Millenium Star Diamond amounting to a whopping $630 million!
I don't dream of owning any of the mentioned diamonds... it would cost me a lifetime. I will just satisfy my at-the-moment wanting for diamond by looking at jewelry shop displays and the internet.