My good friend Jen has an Etsy boutique called Plastique*, where she has debuted her collection of inverted "diamond" rings. I absolutely love them (we schemed and dreamed about the design and specifics regarding how each ring would work months ago and she surprised me at Christmas by showing me the finished product), and I bought one in different colors for all of my (oh my word I can't believe I'm going to say what I'm about to say, somebody kill me now. Seriously. Now. I never EVER thought I'd be the type of girl who would refer to her girl friends as...) girlfriends for pre-Christmas presents.
At ten bucks a pop, these diamond rings are the type of jewelry you can buy in bulk. Check out her store here.