Zirconium dioxide for aesthetic reasons, or of 2) strong, extremely durable dental prostheses constructed entirely from monolithic zirconia, with limited but constantly improving aesthetics. Zirconia stabilized with yttria (yttrium oxide), known as yttria-stabilized zirconia, can be used as a strong base material in some full ceramic crown restorations. Transformation toughened zirconia is used to make ceramic knives. Because of the hardness, ceramic-edged cutlery stays sharp longer than steel edged products. Due to its infusibility and brilliant luminosity when incandescent, it was used as an ingredient of sticks for limelight. Zirconia has been proposed to electrolyze carbon monoxide and oxygen from the atmosphere
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