I had originally posted the below here:
http://www.theroyalforums.com/forums/f20/catherine-middleton-jewellery-29261-7.html but after discovering this thread (which is more about prospective jewels), I think it fits better here...hope the cross-posting is okay. Thanks
Hi everyone, I'm new to posting in these forums but have been lurking for a while, since the big engagement

I've spent the last couple of days pouring over various Princess Diana jewelry websites to try to figure out which jewels we might see Kate in. I was trying to get a sense of what jewels Diana personally owned and would therefore pass on to the boys and then their wives, but it was hard to find out the info. Kate's style is so conservative, but I can't wait to see her decked out in some great sparklies!! (Slightly OT, but if anyone wants a GREAT site to drool over...er, I mean, to see all of Di's jewels, this site is great!
Diana's Jewels)
For someone up-thread asking about the Cambridge Lovers Knot tiara, from what I read on other websites, it was gifted to Diana when she married Charles - from the Queen, from her personal collection (i.e. not the Crown Jewels) - but upon their divorce, she returned the tiara to the Queen. I can understand it was an heirloom, but seems weird to have to return a "gift" but maybe, as some others have noted, they were just returned for safe keeping until PW and PH come of age or get married?
At first I wanted to see Kate wear the Strathmore Rose tiara (on the top of her head, not as the QMum wore it) but now I'm hoping that the Queen will have one made just for Kate. Although...I don't like the one made for Sophie, so hopefully it will be better (bigger!) than that one

Also, as gorgeous as I think it it, I don't want to see Kate in the Cambridge Lovers Knot since, to me, that is so iconically Diana (and I don't want any more reasons for more comparisons to be made).
p.s. with regard to the sapphire collection that Diana received from the Saudis, I'd like to see it re-made by PW into something new for Kate. Maybe a necklace with the largest stone in the center and the smaller earring stones as side stones on the necklace. So, using all of the jewels from that collection, but made into something new and modern for his bride (maybe even incorporated into a new tiara for her!). That way his mum is with them through those jewels as well but it's not so instantly recognizable as "Diana."