Gemstone Triple Brass HoopsBrass hoops + Niobium earwire. The Niobium anodized brass color French hook earwires are made in the USA from Niobium, a metal element that is usually able to be worn by people who have metal allergies. The manufacturer states that "Niobium is completely hypoallergenic and with proper care will never tarnish or fade." According to another source, Niobium is always nickel free, because it is a pure metal and not an alloy.