I think the Spencers have three tiaras. The Marie Antionette one is tortoisshell?? I've heard that--I don't know. The other is HIDEOUS. It's all over the Worst Royal Jewels thread. Here's a link
http://photos.case.edu/photo/1774.jpg
I mean UGH. It looks like two tiaras, one of top of the other. Individually, they would be nice, but together--imagine that on Diana on her wedding day. Not so fairytale like now, huh?