Sophie Charlotte, Gemahlin von Prince Eitel Friedrich von Preußen
From eBay.
The puffed sleeves and what looks like a vee-waistline suggest this image could date to the 1890s. This is possible because she was born in 1879. The card's caption also calls her Duchess Sophie Charlotte instead of Princess Eitel-Friedrich.
Keywords: Princess Eitel-Fritz, Princess, Oldenburg family, Hohenzollern family, German, bouffant coiffure, sweetheart neckline, modesty piece, bertha, quarter length puffed sleeves, ruffles, vee waistline, choker necklace, necklace, bracelets, fan