1853 Eugénie de Montijo by Franz Xaver Winterhalter (Versailles)
Empress Eugenie is dressed in an evening dress with all of the trimmings befitting an Empress in this famous 1853 Winterhalter portrait. This may be the most well-known portrait there is of the Empress Eugénie.
A commenter on Webshots, ella1886, made this comment about the portrait, "My understanding is that this was painted by Winterhalter in 1853, presumably to celebrate the wedding of the Countess of Teba to Emperor Napoleon III earlier that year, and provide France with a formal portrait of their new Empress. The painting hangs in the Louvre along with the tiara she's depicted wearing."
Franz Xavier Winterhalter was the leading portraitist of the mid nineteenth century painting the royalty, nobility, and glitterati of the day. His Wikipedia article is here.