In experiments, thin layers of gold—yes, the real deal—allowed visible light to shine through, provided the metal was reduced to a thickness of 100 nanometers (or: gold leaf).

Due to their refractive properties, these two outer layers increase the efficacy of the heating effect. Moreover, the top layer of titanium oxide acts as finish that protects the gold layer from wear.

Gold flecks make super-transparent glass fully opaque from one side. A glare-free window that is opaque from the outside but still offers a clear view from inside could be made with a coating ...