From the French. Literally meaning a “membrane through which passes the light of day”, the easier translation is “open to light”. As the name suggests, it is a favorite technique in decorative arts, especially jewellery.
Developed in France and Italy in the 14th century, this technique has been used largely for making vessels, jewellery, and, in Russia, demitasse spoons. Because it has no metal base, plique-a-jour enamel is exceptionally fragile; therefore, few early specimens are preserved.
In this technique, metal strips or individual wires are used to outline design, exactly as is cloisonné, but these are soldered to each other instead of to the metal base. The unattached support, usually a sheet of metal or mica, can be easily removed after the enamels have been annealed and cooled. The remaining shell of transparent or translucent enamel gives the effect of jewel-like stained glass in miniature. The enamels can be carefully polished to enhance their appearance