Niobium is one of the more exotic metals to figure prominently in jewelry. While it's certainly rare and pricey enough to merit being sold as jewelry the main attraction is actually its ability to form very thin films of many different colors. Anodization, the process by which a metal is selectively oxidized at an anode in an electrolytic bath, goes hand in hand with niobium destined for jewelry. Niobium oxide has the ability to diffract light at specific wavelengths depending on the thickness. The thinnest layers, measuring only a few atoms across, will impart a brown tinge and as the thickness increases it goes through blue, purple, red and green with many shades in between. So here's a perfect chance to liven up your set with a little of this handsome metal!