smalto
/ˈsmaltəʊ/noun
Coloured glass or enamel used for mosaic work, etc.; a small cube or piece of this.
Origin
Early 18th century; earliest use found in Joseph Addison (1672–1719), writer and politician. From Italian smalto from the unattested Franconian etymon of post-classical Latin smaltum and of the Romance words cited at amel.