This dates to 1878 or 1879 given it is an engagement photo.
From pinterest.com/hansatingsuwan/royals-fiancée-engagement/; sepia tone removed.
Maria Cristina wears a complex dress with a short tablier and a triangular panel running from neckline and shoulders to her actual waistline.
Keywords: 1879, Debas, María Cristina Habsburg, Archduchess, Queen, Habsburg family, Borbón family, Austrian, bangs, feathered hat, high neckline, bertha, elbow length tight sleeves, bows, lace cuffs, natural waistline, tablier, buttons, over-skirt, bustle, under-skirt, drapery, train, floral bodice ornament, choker necklace, bracelets, parasol