Nanoscale engineering of gold particles in 18th century Böttger lusters and glazes.

SignificanceThe exploration of gold-based colorants in glass and glazes led Nobel Laureate Richard Zsigmondy to the study of colloids, and to the development, with Henry Siedentopf, of the earliest microscopes capable of resolving such small length scales. Zsigmondy's studies were preceded by alchemical investigations starting in the 17th century that yielded the gold-based Purple of Cassius, and experiments in the early 18th century resulting in an unusual purple iridescent porcelain overglaze, called Böttger luster, at the Meissen Manufactory. We discuss the first nano-scale characterization of Böttger luster, its successful replication, and propose an explanation for its optical properties based on the physics of scattering and interference of nanoparticle arrays.