Zirconium for use in jewelry. Zirconia is a component in some abrasives, such as grinding wheels and sandpaper. A small fraction of the zircon is converted to the metal, which finds various niche applications. Because of zirconium's excellent resistance to corrosion, it is often used as an alloying agent in materials that are exposed to aggressive environments, such as surgical appliances, light filaments, and watch cases. The high reactivity of zirconium with oxygen at high temperatures is exploited in some specialised applications such as explosive primers and as getters in vacuum tubes. The same property is (probably) the purpose of including
Zirconium dioxide coatings; it is a high-index material usable from the near-UV to the mid-IR, due to its low absorption in this spectral region. In such applications, it is typically deposited by PVD. In jewelry making, some watch cases are advertised as being "black zirconium oxide". In 2015 Omega released a fully ZrO watch named "The Dark Side of The Moon" with ceramic case, bezel, pushers and clasp, advertising it as four times harder than stainless steel and therefore much more resistant to scratches during everyday use. Single crystals of the cubic phase of zirconia are commonly used as diamond simulant in