Louise Henriette looks like a teenage girl in this portrait, and a young tenager at that. That would date this to 1640 or not long thereafter.
From bndestem.nl/breda/michiel-smits-de-jan-hoppen-van-brandenburg~ad13f955/; spots removed with Photoshop.
This dress is very simple and the adornment comes from her body, the jewelry, wrap, and the white chemise.
Keywords: Louise Henriëtte van Nassau, gravin van Nassau, Luise Henriette von Oranien, Kurfürstin von Brandenburg, Countess Louise Henriette of Nassau, Orange family, Hohenzollern family, Countess, Princess, proto-hurluberlu coiffure, hair jewelry, necklace, chemise, off shoulder scoop neckline, elbow length under-sleeves, full cuffs, clasps, fitted bodice, elbow length full over-sleeves, vee waistline, close skirt, wrap