Nordic Royal™ is an alloy of copper with aluminium and zinc, giving it a rich golden through-colour and making it very stable.
It has a thin protective oxide layer containing all three alloy elements when produced. As a result, the surface retains its golden color and simply loses some of its sheen as the oxide layer thickens with exposure to the atmosphere to give it a matte finish. It behaves differently from other Aurubis copper products over time and does not develop a blue or green patina.