I've not seen the black officer ring, but I do have two sisters who have the amythest (how do you spell that?!?) in silver, and it is gorgeous. Shiny and blingy and everything!
I don't know why I cant picture their hands, but I'm pretty sure they both were them on their right ring finger. Maybe their right pointer finger? Almost positive not their middle finger, though. If you do get it, report back on it!