Niobium is very similar to titanium but is much softer and more flexible and is therefore widely used in jewelry that is bent open and closed, such as the so-called “seam rings”. Pure niobium does not have an ASTM code, but because this material has been used for so long, it is generally recognized that this material can be used safely. Niobium, like titanium, can be anodised in all kinds of colors.