Vintage view: Glittering enamel work known as guilloché

A form of what is termed, allochromatic glass, enamel is used to apply coloured, high shine detail to a metal object, and even in the hands of a master it is notoriously difficult work.

It’s a mixture of iron oxide, potassium oxide (potash), quartz sand, and borax coloured with metal oxides, crushed and then heated together.