Zirconium dioxide

Zirconium dioxide (ZrO2) has very good mechanical properties both when cold and at high temperatures. At ambient temperatures, its thermal conductivity is low.
At temperatures above 1000°C, zirconium oxide is a very good electrical conductor. It is also very hard, wear-resistant, chemically inert and resists attack by metals.
Zirconium oxide can be colored for use in jewelry.