This is a 'coloured' glass, also popular in the 1220s-1280s Medieval period. However, this was not like stained glass. It was produced by making clear glass, incising cross-hatching parallel lines in this and filling them. The grooves were filled by an iron-lead paste, or crushed glass fragments, and gummed in to stay in place. Some Medieval grisaille has occasionally survived the iconoclasm of the Reformation or later replacement.