The Mineral & Jem Display at the Natural History Museum
Huge diamonds - I think the 10carat round (I am going by memory so that could be wrong) would look quite nice in my current setting :-) and Marie Antoinette's 20 carat earrings would also look lovely!
a bejeweled ring
more crazy necklaces
more huge rocks
...and...the Hope Diamond
Just so you know you could lose an eye by being short and trying to see the hope diamond. Those ladies and gents are vicious trying to get their photos. At one point I thought I was going to stand there all day when people would not let me AWAY from the display...then they realized that the display rotated and I was no longer on the "good" side! :-)