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
Cubic zirconia a strong, complex rare earth absorption spectrum. Discovered in 1892, the yellowish monoclinic mineral baddeleyite is a natural form of zirconium oxide. The high melting point of zirconia (2750 °C or 4976 °F) hinders controlled growth of single crystals. However, stabilization of cubic zirconium oxide had been realized early on, with the synthetic product "stabilized zirconia" introduced in 1929. Although cubic, it was in the form of a polycrystalline ceramic: it was used as a refractory material, highly resistant to chemical and thermal attack (up to 2540 °C or 4604 °F). In 1937, German mineralogists M. V. Stackelberg and K.