Cranberry glass

Gold ruby glass is a collective term for pink to dark red glasses that are colored in the glass melt with dissolved, colloidal gold. Performance pigment color is gold purple. The color is not black at a greater layer thickness. The coloring is only imperfectly visible in the cooling from the melt glass and appears only when reheated in its full color strength, because it is a so-called tarnish. By diffusion processes, the colloidal particles are formed in the glass during the re- warming. The color of gold ruby glass is produced by the excitation of plasmons, the plasmon resonance frequency is dependent on the size and shape of the gold nanoparticles. For spherical gold nanoparticles, the resonant frequency is typically 510 to 540 nm, leading to the typical red color of the glass.

It can be dyed, among other soda-lime glass and lead to the gold ruby glass. Most gold ruby ​​glasses commercially available contain certain amounts of lead oxide as the support the formation of colloids. Another ingredient is often tin which is added in metallic form, as a reducing agent. In borosilicate glass is pink -violet staining by the vapor deposition of gold can be produced.

Use eg as drinking glasses, glass window, glass traffic light. It has been almost completely supplanted by the much cheaper and more yellowish selenium ruby glass. In addition, there is often a slight brown copper ruby glass.

This type of glass stain was first mentioned by Anthony Neri in L' Arte Vetraria (Chapter 129 in the 7th book ). It was Johann Christian Orschall of 1682 published a production recipe for ruby glass. John Kunckle refined the recipes later for production.