From lapis lazuli to synthetic ultramarines: a μ-Raman spectroscopy investigation on the history and development of “the Most Perfect” Color

Natural ultramarine has been one of the most precious blue pigments employed in the past in the artifacts. It is typically obtained by crushing and grinding the lapis lazuli rock and selectively extracting the blue mineral lazurite. Since the early 19th century, when the synthetic version was produced, the use of this much less expensive material became widespread, and synthetic ultramarine blue replaced the natural one in painting palettes. The present study is conducted as a preliminary μ-Raman investigation for creating a comprehensive and detailed database of the ultramarine pigments, both natural and synthetic, employed over the centuries until today.