This is synthetically produced Sapphire. Single crystal Sapphire has a high thermal conductivity, volume resistivity, hardness and wear resistance, as well as a high upper use temperature. Sapphire is a transparent material having useful transmission of wavelengths in the range 0.2 to 5.5 microns. It is much stronger than glass and can be used as viewing windows in high pressure and vacuum applications. It is a superior alternative to quartz, alumina, and silicon carbide in semiconductor processing applications. In addition, Sapphire tubes are used in various analytical instruments in lamp applications that transmit visible, infrared or ultraviolet light, often with high intensity at high temperatures and pressures.