belle badgley mischka blue dress Belle Badgley Mischka Women's Dress Maeve Size 6 Blue Sky Bell Sleeve NWT 21

Graceful yet quietly commanding, this Regency Era black empire waist gown captures the restrained elegance of early 19th-century fashion

Make her birthday wishes come true with this darling Cinderelly Dress featuring a statement bow neckline, layered pleated skirt, and dreamy silhouette

Details: Adjustable straps, cowl front

From the back, the open-back construction lets the corset boning take center stage the seam lines continue in a clean V shape down toward the waist, making the back view just as photogenic as the front

Since you can't buy Kate's exact same piece, check out a few Duchess-inspired garden party looks here: