I'm pretty plain-jane when it comes to jewellery. All I wear on my bike are a watch, my wedding bands, and a silver rope necklace with a Maori greenstone pendant which is supposed to bring the wearer strength. I need all of that I can get. I probably shouldn't wear it cycling, but it was given to me by a dear friend and I just can't seem to take it off.
I have a few flash pieces I can wear when I have to do the formal thing, which fortunately isn't very often. My only real concession to jewellery is my watch collection, which is kinda out of control at this point.