The high melting point of ≈ 2050°C and the transmission capacity of sapphire in a wide wavelength range from 0.2 to 5 µm make it an indispensable material for the manufacture of optical elements and viewing windows. In addition, this replacement, for example, of quartz with sapphire in viewing windows, is facilitated by the durability of the material due to its high abrasion resistance. Optical elements and viewing windows are produced at the enterprise in the form of ground and polished round products with a diameter of up to 280 mm and rectangular products with sides up to 280 mm. Orientations of optical elements c, a, r, m are possible. In any case, the maximum dimensions when ordering must be specified separately, as well as the quality category of products.