Grisaille (pronounced GREES-eye) is a technique of painting in monochrome, often grey, brown (brunaille) or green (verdaille). It was used not only in painting, but also in architecture, including stained glass windows. The technique emerged during the 12th century and reached a pinnacle in the 14th century.
Grisaille is accomplished by painting on light glass using a mixture of ground glass, ground lead and other substances. This mixture is vitrifiable (able to be fired and turned into glass). Diane de Poitiers commissioned windows done with the technique.
In 1548, Nicolas Beaurain completed a set of these windows for the great hall at Anet.