The item is a copper impression of the Empress Charlotte of Mexico.
Princess Charlotte of Belgium was the daughter of King Leopold I of the Belgians and Princess Louise d'Orleans. At the age of 17, Charlotte married Archduke Maximilian of Austria. In 1864 Maximilian and Charlotte became the Emperor and Empress of the Second Mexican Empire. Sadly, the couple's reign, and indeed the Mexican Empire, came to an end in 1867 when the Emperor Maximilian was executed by the rebel forces of Benito Juarez.
The Empress Charlotte died in 1927 aged eighty-six. She had been insane for sixty years, having lost her mind shortly before the tragic death of her husband in 1867.
The following words appear around the image of the last Mexican Empress: "CARLOTA ... EMPERATRIZ ... MEXICO 1866"