C 1900 French plique-a-jour enamelled gold brooch with some small rose cut diamonds.
Measurements : 24×22 mm
Plique-à-jour (French for “letting in daylight”) is a vitreous enamelling technique where the enamel is applied in cells, similar to cloisonné, but with no backing in the final product, so light can shine through the transparent or translucent enamel. It is in effect a miniature version of stained-glass and is considered very challenging technically: high time consumption (up to 4 months per item), with a high failure rate. The technique is similar to that of cloisonné, but using a temporary backing that after firing is dissolved by acid or rubbed away. A different technique relies solely on surface tension, for smaller areas. In Japan the technique is known as shotai-jippo (shotai shippo), and is found from the 19th century on.