Sapphire optics that have 9-Mohs surface hardness, have thermal stability to 2000 °C and can withstand pressures up to 4000 psi, depending on configuration, are available from Meller Optics Inc. The company will custom manufacture them as spherical from 0.005 to 0.5 in. in diameter, planoconvex and -concave shapes from 0.5 to 6 in. in diameter, and rectangles and squares of various thicknesses. They transmit from 270 nm to 4.7 µm with up to 85% transmission uncoated and up to 99% with antireflection coatings on two sides.