Thick colored glass cast into a concrete or resin matrix is called dalle de verre.
The French term means “glass slab.” Instead of joining thin pieces with lead came, the artist cuts or chips thick slabs of colored glass and embeds them in a supporting matrix, traditionally concrete. The resulting windows can have strong jewel-like color and a bold, sculptural texture.
Dalle de verre became especially prominent in the 20th century, when architects and artists explored large abstract windows. The thickness of the glass and the chipped edges scatter light differently from conventional sheet stained glass.
Dalle de verre is sometimes described informally as concrete-and-glass stained glass, but that wording does not name the technique. It is also unrelated to flashed glass, which involves a thin colored layer fused onto another glass body.