Ultramarine is a blue pigment consisting primarily of a zeolite-based mineral containing small amounts of sulfur. Ultramarine is one of the most complex of the mineral pigments, composed of the blue mineral lazurite, which is the major component of the rare and semi-precious stone lapis lazuli.[1] The mineral occurs in nature as a product of limestone metamorphism and typically is associated with calcite, pyrite, diopside, humite, forsterite, hauyne and muscovite minerals, and is sometimes found in lava as a by-product of volcanic eruptions.[2]
...

Rembrandt Harmenszoon van Rijn (15 July 1606 – 4 October 1669) was a Dutch painter and etcher. He is generally considered one of the greatest painters and printmakers in European art history and the most important in Dutch history.

The range of color Rembrandt employed falls firmly within the mainstream ...

Gilbert Charles Stuart (born Stewart) (December 3, 1755–July 9, 1828) was an American painter from Rhode Island. According to evidence from various sources, his palette consisted mostly of the following:

• Antwerp blue (a modification of Prussian blue)
• Yellow ochre
• Vermilion
• Madder lake
• Burnt umber ...