In 1828, Jean-Baptist Guimet won a 6,000 French Franc prize for his synthesis of a compound that matched the structure of pure Lapis Lazuli (Lazurite), the blue that had become, in some cultures, more precious and costly than gold. The Lapis best suited to making fine pigment was not the stone that today is considered ‘gem grade’ (which, if rendered into pigment, produces a gray, ash-hued colour). The Lapis best suited to make Ultramarine is a deep purple stone found early in mines located in Badakshan, in a highly inaccessible region in what, today, is northeast Afghanistan.
Guimet’s Ultramarine was economical to produce and, to this day, is an excellent match to clarity and brilliance of the nearly mythical Lapis. Within a short time, the pigment became available commercially and Winsor & Newton began producing it in water colour in 1832. It is a deeply saturated, transparent blue, well-suited to clean mixing. It offers proven stability and (in water colour) it flocculates (an electro-chemical response in which pigments clump together in an effect that is similar to granulation).

Complex sodium alumino-silicate containing sulphur. PB29
A – Permanent (bleached by acids, acidic atmospheres); ASTM I
Series 2
Transparent
Granulating