Plique a Jour is not so much a fancy French greeting as it is an expert jewelry technique that had its hey-day in the Art Nouveau movement. During that period the focus for jewelry was on the world of nature all around us. So artful renderings of flowers, birds and bugs came to the fore.
Plique-à-jour or French for glimpse of daylight is a vitreous enameling technique wherein enamel is applied directly into wire cells of an item's design, with no backing to the piece so light can shine through the transparent or translucent enamel producing an often realistic result.
One of the most effective uses of this charming technique is with insect wings--since in the real world, an insect's wings are often translucent themselves.
But why should I rattle on and on about it when you can see this process for yourself.
Are you feeling it? What an art form!