Zaffre, a pre-scientific substance (see List of alchemical substances), is a deep blue pigment

Pigment

A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...

 obtained by roasting cobalt

Cobalt

Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....

 ore

Ore

An ore is a type of rock that contains minerals with important elements including metals. The ores are extracted through mining; these are then refined to extract the valuable element....

, and is made of either an impure form cobalt oxide or impure cobalt arseniate. During the Victorian Era

Victorian era

The Victorian era of British history was the period of Queen Victoria's reign from 20 June 1837 until her death on 22 January 1901. It was a long period of peace, prosperity, refined sensibilities and national self-confidence...

, zaffre was used to prepare smalt

Smalt

Smalt is powdered glass, colored to a deep powder blue hue using cobalt ions derived from cobalt oxide . Smalt is used as a pigment in painting, and for surface decoration of other types of glass and ceramics, and other media...

 and stain glass blue.

The first recorded use of zaffre as a color name in English

English language

English is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...

 was sometime in the 1550s (exact year uncertain).