Research workers at Corning Glass have developed what they believe to be the first color photographic medium having true color permanence. The medium is a photosensitive glass capable of being developed to give patterns using the complete spectrum of colors and varying degrees of opacity in two or three dimensions. The optical transmission of the glass is a mix of absorption of isotropic and elongated silver at the pyramidal apices. The color finally produced, which varies right through the spectrum, depends on the elongation of the pyramids. The final color varies according to the flux of the first UV exposure.