Abstract: A decorative panel which simulates the exposed surfaces of installed glass blocks. The panel, which is transparent, semi-transparent or translucent, has a variety of configurations simulating various combinations of 2", 3", 4", 6", and 12" glass blocks such that an installation of the panels in adjacent relationship can be adapted on-site to provide almost any rectangular planar area with the glass block effect. Each of the panels is adhesively secured to an existing planar glass surface therebeneath. A layer of air trapped between each of the relatively thin panels and the underlying glass surface provides a thermal barrier for insulating purposes. The underside of the panels can be tinted, frosted, etched or sculpted whereby a window containing the underlying glass surface is rendered translucent, providing visual security.