Niobium is a naturally inert metal that is non-reactive with the human body. Niobium is naturally a blueish color, but it can be anodized in order to give it a gold tone. Niobium is anodized by placing the metal in a specific solution of soap and water and applying an electrical current. Unlike typical fashion jewelry, anodized Niobium does not have any plating, coatings or dyes; after the anodization process it is still 100% pure Niobium which means it is still 100% non-allergenic and non-reactive.
Since Niobium is naturally non-allergenic, and it's color can be changed without adding any foreign or reactive materials, it is an excellent metal for earrings. Niobium earrings can be worn safely without any allergic reactions and without worrying about a plating or coating that will eventually wear away.