For those who want to give the impression of being a hero, while secretly being the villain, this ring is for you. Created by What's Your Passion Jewelry, this 19mm diameter ring has S.H.I.E.L.D's logo emblazoned on the front, overlaid with 18kt gold. Meanwhile the inner ring reveals your true affiliation to HYDRA.
Aside from the fact that it looks cool and is actually well made, the rings were crafted from Marvel's actual schematics. It even comes with an official certificate of authenticity. If you are looking to invest in a nice collectors item, or just want to buy a ring that gives you some geek cred, this item is it.
You can order it directly from their site.