Empress Wu Zetian ingested pearl powder, which was thought to stimulate skin healing, as well as applied it to her face to brighten her complexion. White lead was also discovered to be an effective whitener, but it is difficult to pinpoint when lead-based pigments were first used for cosmetic purposes in ancient China. Some sources suggest ceruse may have been in use in very ancient times, as far back as the Shang dynasty (c. 1600–1046 BC), partly due to a literary allusion to powder made from roasted lead, and partly because it’s possible that the manufacturing of lead pigments in ancient China dates back as far as lead metallurgy —the process of separating the metal from its ore—itself. “White may be said to represent light, without which no color can be seen.” —Leonardo da Vinci Ceruse was made by combining lead and sharp vinegar, which was left to steep until it formed a skin, after which the process was repeated until the lead became a powder, a procedure remarkably similar to the Greek and later Roman methods. Ceruse continued to be used, at least by upper-class women who could get hold of it, for roughly the next 350 years; it was briefly out of favor during the Sui dynasty, as the empress did not use it, but became popular again under the Tang emperors. It was in this latter period that the growth of trade meant that ceruse spread to Japan, where it was used by ladies of the court until the late sixteenth century, by which point it became widely available to all women.