A thick disc of pressed glass, moulded into hundreds of radial prisms that run from a small centre boss out to a fluted edge, mounted on a brass back plate. The light sits behind it, so every prism fires at a slightly different angle and the whole face breaks into fine points of amber and clear. It is a piece of glassmaking that belongs to the nineteen-thirties and has come round again. On a plain wall in a corridor, lit at night, it does the work of something twice the price.
