It is a natural element found in our earth. It has the symbol Zr and the atomic number 40. It’s natural colour is a greyish, silvery-white.
Zirconium has a super high resistance to corrosion. For many years, it has been used in the space, aeronautic and even the medical industry. It is bio-compatible and non-toxic.
The ring is heated to a very high temperature. The extreme heat causes a chemical reaction on the surface of the zirconium, and the result is a beautiful black colour. This black layer is actually the oxidation that took place. The oxidation layer is extremely hard, yes you can scratch it, but it’s tough to do.
And the black colour is permanent. It does not fade, tarnish, or otherwise change colour. To get a two tone look a diamond tool is used to cut through the black oxidised shell. The underlying colour is grey-silver. So you can create a striking pattern on the ring this way.