Gold, enamel.
Size 59 x 54 mm.
Weight 35.05 g.
Marked with St. Petersburg assay officer year mark "185?".
Marks.
Under different light.
Alledgedly awarded in 1854 to Armand Barthélemy Dominique Jacques, marquis de Castelbajac (1787-1864).
Text of nomination letter from Nicolas I.
"To General Marquis de Castelbajac
General, The mission that You have so honorably fulfilled in Russia has enabled me to appreciate the elevation of Your character, the nobility of Your intentions and the rectitude of Your Principles It is with unabated zeal that You have devoted your loyal efforts to establishing good relations between Russia and France. Although they were not crowned with success, it is important for me to recognize this and to offer You a conspicuous testimony of my feelings of true esteem and friendship for You. I therefore send You the insignia of my Order of St Alexander Nevsky and renew to You on this occasion the assurance of my attachment.
Nicolas
St Petersburg on January 27, 1854."
It seems that marquis de Castelbajac also purchased a silver-made breast star from Ouizille Lemoine workshop
https://asiamedals.info/threads/imperial-russian-orders-made-by-ouizille-lemoine-paris.23589/
Silver.
Size 83.5 mm.
Circa 1854-1863.
Reverse plaque reads "Ouizille Lemoine, Joailliers bijoutiers de la Légion d'honneur rue du Bac n°1 Paris".
asiamedals.info