Niobium is a light gray base metal that is typically anodized into six different colors. This process involves putting the metal item into an acid bath and passing an electric current through the tank. Oxygen atoms bond to the item's surface, which creates a lustrous sheen. Some of the nicest specimens we've seen have been earrings -- though one can find niobium bracelets, beads, pendants, and more. These beautiful earrings, offered by Sozra Gallery of Jewelry and Art, are a good example of this stunning, rainbow-like material. Finding Niobium can be tricky, but it's worth the effort. Many who are allergic to certain metals (such as aluminum, titanium, and magnesium) can almost always tolerate them when they are anodized with niobium.