An improved method of producing transparent diamond laminates employs a substrate which is removed once a second layer is deposited over the diamond coating, thereby exposing a smooth diamond surface. The second coating should have a refractive index substantially identical to diamond, with zinc selenide and titanium dioxide being particularly preferred. Diamond films having two smooth surfaces may be produced by simultaneous deposition on parallel, opposed substrates until the two diamond films merge together to form a single film or plate, followed by removal of at least a portion of the two substrates.