I like Tiffany diamonds by the yard, personally. Hoping for one!
Right now, if I want to wear something small and unobtrusive, I wear a yellow sapphire pendant my DH bought me a few years ago, on an 18K Italian white gold chain. Nothing too exciting, but a little bit of sparkle in an interesting color. It has a vaguely diModolo feel, but DH bought it from his mom's favorite jeweler.
I am more of a large necklace girl, though, even for everyday wear, especially vintage Native American pieces my grandfather collected for my mother and grandmother. And when I say large, I mean BIG. (The Zuni pendant is several inches across!)