Zirconium is a silvery-white metal that can be found in the periodic table under the symbol Zr. In the world of jewellery, it is mainly used for black rings, as a hard but thin oxide layer forms when the metal is heated. This provides a striking black-grey colour with a noble shine. The hardness of this oxide layer is similar to that of a sapphire, which has a Mohs hardness of 8 to 9. Zirconium is the only metal that can form a naturally black surface without losing its malleability. Another advantage is its durability: as the oxide layer is an integral part of the material, it does not fade or corrode. Zirconium jewellery is therefore particularly scratch and corrosion resistant. The protective layer also prevents tarnishing and ensures a lasting lustre. In addition to its high resistance, zirconium is also lightweight and comfortable to wear. These properties make the metal a modern and high-quality material in jewellery production - particularly popular for wedding rings and partner rings.