Colour: Light Grey
Moh's Hardness: 5
Zirconium is a metal that is harder than platinum and 100% hypoallergenic. It can be blackened with a heat treatment that penetrates the surface, which makes it longer lasting than plating.
First discovered in 1789 by Martin Heinrich Klaproth in Berlin, the name zirconium comes from the Persian word ‘zargon’ meaning gold-like. Today most zirconium is mined in Australia and South Africa.
Zirconium has a very high melting temperature so is usually milled or lathed from a solid block for jewellery purposes. To turn it black, it is exposed to a high temperature for several hours. The extreme heat causes a chemical reaction on the surface of the zirconium and creates a long lasting black finish which can be polished or made matte.
In the jewellery industry it is noted for its resistance to corrosion, and is often aligned with titanium and tungsten carbide as a light and hard wearing metal for the production of rings. It cannot be soldered like gold and silver so jewellery applications are limited but gems can be set into zirconium.
While zirconium is hard wearing, it can still be scratched. It’s best to remove if you’re doing anything where the ring will come into contact with steel or hard metals. Avoid acids, alkaline solutions and harsh chemicals. To clean, simply wash in warm soapy water and dry with a soft cloth.
If your zirconium piece has been blackened, it can be re-blackened, only if no stones have been set. Should the black start to wear away, the colour can always be professionally removed and taken back to its natural gunmetal grey colour. This is applicable even if stones have been set.