Dalle de verre is the French term for stained glass made from thick slabs of cast glass set in concrete or epoxy.
Unlike traditional stained glass, which usually uses thin glass pieces joined by lead cames, dalle de verre uses slabs commonly about 20 millimetres thick. Artists cut or chip the slabs to shape, and the pieces are assembled in a supporting matrix such as concrete, resin, or epoxy.
The thick glass can be faceted with a hammer or other tools. These roughened surfaces scatter light and create a strong, jewel-like effect. The technique became especially prominent in modern architecture during the 20th century, when designers wanted large, durable, abstract fields of colored light.
Dalle de verre is sometimes described casually as “concrete stained glass,” but the French term refers specifically to the slab-glass method. It should not be confused with grisaille, a monochrome painted-glass technique, or verre églomisé, a form of gilded glass decoration.