Dalle de verre is the stained-glass technique that uses thick slabs of colored glass set in an epoxy or concrete matrix.
The French term literally refers to glass slabs. Instead of cutting thin sheets and joining them with lead came, artists cut or fracture thick pieces of cast glass and embed them in a supporting material. The exposed edges can catch and scatter light, producing a bold, jewel-like effect.
The method became especially prominent in twentieth-century ecclesiastical architecture. Concrete was used in some early and major examples, while epoxy resin became another important matrix because it could hold pieces together with less visual bulk.
Dalle de verre is sometimes mistaken for ordinary mosaic stained glass because both use individually cut pieces. Its defining feature is the unusually thick slab glass and the matrix that supports it.