A system and method for diamond based multilayer antireflective coating for optical windows are provided. An antireflective coatings for optical windows may include an optical grade silicon substrate, a first polycrystalline diamond film on the silicon substrate, a germanium film on the first polycrystalline diamond film, a fused silica film on the germanium film; and a second polycrystalline diamond film on the fused silica film. A method of fabricating a diamond based multilayer antireflective coating may include the steps of cleaning and seeding an optical substrate, forming a first diamond layer on the optical substrate, forming a germanium layer on the first diamond layer, forming a fused silica layer on the germanium layer, cleaning and seeding the germanium layer, and forming a second diamond layer on the germanium layer.