Today's sparkly thing is a pendant of gold set with diamonds that also doubles as a locket. The front of the locket features the head and shoulders of a woman. Instead of a photo, the locket conceals a handy mirror.
The female form was an important theme in Art Nouveau jewelry and the entire movement glorified the idea of idealized feminine beauty. This is personified here with this depiction of a graceful woman with flowing, upswept hair.
The gold relief is the work of Georges van der Straeten who was a sculptor born in Ghent in 1856 and who worked mainly in Paris until his death in 1928. It is inscribed on the reverse 'Monte Carlo 13 March 1901' around a sprig of mistletoe.