Luna's is silk and satin, with diamond-encrested crown and boots. Her hair is tied in a ponytail and she has a diamond necklace.
Celestia's dress is sequin-covered gold silk with pastel ruffles underneath. Her hair is also in a ponytail because i had no idea what else I should do with it.
Cadance is my personal favorite, with her curled and braided hair and regal satin dress. Her boots and crown are also crested with diamonds.
Enjoy! Made on Adobe Illustrator.