Here comes the sun
The sunburst as a decorative motif probably has its roots in the halos surrounding saintly figures in medieval religious art. During the 17th century, the Catholic church began using elaborate monstrances — decorative stands used to display the communion wafer — adorned with gilded rays. Churches in Italy (most famously St. Peter’s Basilica in Rome, below right) often had gilded sunbursts above the altar.
There is a rare depiction of a convex mirror with a sunburst motif in the background of the Arnolfini portrait by 15th-century painter Jan van Eyck, suggesting that sunburst mirrors have been around for a long time.
Early mirrors were small and convex; it wasn’t until the late 17th century, when Louis XIV established his own glassworks in France, that the world saw a significant improvement in the quality and size of mirrors. But even then, mirrors of any kind were expensive rarities — a 40- by 36-inch mirror sold at the end of the 17th century would have cost the equivalent of $36,000 today. Traditionally, the sunburst mirror was attributed to king Louis XIV of France, who history refers to as the self-styled “Sun King”. In fact, he chose the head of Apollo surrounded by rays of light as his personal emblem (depicted, among many other places, on the gates of Versailles, below). The story goes that the king used to stare into his sunburst mirror each morning to contemplate his face in the center of the sun’s rays.
The early 19th century saw a resurgence in popularity for small, convex mirrors. By this time mirror production had fully taken off, and mirrors became a popular decorative and functional accessory in the home, both in Europe and America. A perfect example is this fanciful set of 3 French Art Deco silver and gold gilt tole sunburst mirrors from the 1930's, from epoca.
One cannot talk about sunburst mirrors without mentioning the iconic work of Line Vautrin, French jewelry maker, designer, and decorative artist. Vautrin's work was both elegant and innovative. She created most of her mid-century Modernist pieces through the process of experimentation, achieving popularity after her involvement in the Paris International Exhibition in 1937 – her iconic work remains highly collectable to this day.
Below from Guy Regal: Sun Mirror by Line Vautrin, 1953. Made of talosel and resin. Talosel is a resin material invented by Vautrin. It is derived from cellulose acetate and the name is shortened form of «acetate de cellulose elabore».
Below from Milord Antiques: (left) Amber glass and talosel resin convex mirror by Line Vautrin, circa 1950. (right) Talosel and resin convex "Gerbera" mirror by Line Vautrin, circa 1955.