Inorganic – Aureolin (Cobalt Yellow) is a transparent, straw, ochre like yellow with strange yet rich greenish undertones. It was produced in the 1850s as an inorganic replacement for the unreliable organic yellow gum known as Gamboge. In glazes and thinned layers, it displays a Renaissance-like range of muted gold which over whites can be quite fiery. However, in or over deeper layers, Aureolin exhibits a mustardy, heavier patina. Mixed with PV 23 it can make a most remarkable deep gingery colour.