I hadn't really thought about broaches (but that would probably be for similar reasons, Valia), but I can see a few people wearing them, now that Lady Galadriel has mentioned some ideas. It's probably just me, but I have a hard time seeing very many broaches that could be Narnian and fit their type of dress. But as mentioned before, that could just be because I can never get broaches to match my outfits.
I also imagine some Narnians would wear flower crowns:
http://trendybride.net/wp-content/uploa ... eils-7.jpg
I think more of the bands would be made out of actual flowers, like this:
https://img0.etsystatic.com/039/1/80217 ... 8_7aov.jpg
For an actual crown a queen might wear would be some sort of circlet, perhaps something similar to this:
http://www.medievalbridalfashions.com/c ... rclet2.JPG
http://www.craftyfox.com/images/Ivy-cir ... w-garn.jpg
There are just so many pretty circlets I could imagine a Narnian Queen (or King, for some of them) wearing, but those looked like they would probably work for everyday wear.
I've honestly never given very much thought to Narnian jewellery before. It's such a natural world, primarily populated with Talking Animals and wood and water spirits. Just about the only people that might possibly to be interested in wearing jewellery would be humans and the dwarfs, considering that they're metalworkers.
I remember Lewis describing the crowns as being light and beautiful and easy to wear (I think they did a really nice job capturing this with Lucy and Susan's crowns in LWW), but I can't really remember any other jewellery mentioned. It seems like I can recall people wearing garlands on their heads much more easily than I can think of times that Lewis referenced some sort of gold or silver finery.
I do really hope that they stick to Lewis's description for Shasta/Cor's crown in HHB; I've always loved the simplistic look of crowns that are a thin band of gold. It doesn't look pretentious at all and I think it really suits his age and rank as a prince.