Thin transparent films of diamond have been grown only by chemical vapor deposition (CVD) methods at slow rates. Using a hot filament CVD reactor of large area (30 cm x 40 cm), these films were deposited onto highly polished copper substrate at a rate of about 1 mum h(-1). The cost of manufacturing thin transparent films of 20 mum thickness may be as low as $1 cm(-2). At such a low cost, thin transparent films should have diversified applications, such as X-ray windows, high frequency (up to 10 GHz) SAW filters, and other advanced devices.