In the Anime, Rosette appears in several outfits. She most often depicted in a blue short-sleeved dress with a veil, boots, gloves, and complete with side-pouches. When Rosette tends to chores around the Order she is portrayed wearing a similar outfit that is slightly more conservative with long sleeves.
In Episode 3: The Apostles, Rosette is sent to retrieve Azmaria Hendric and goes undercover in a sexy pink dress.
In Episode 9: Joshua and Episode 10: Horn, the anime takes time to relay an important backstory. A younger Rosette is depicted wearing two outfits.
Episode 12: Holy Night is a Christmas themed episode. Therefore, it is appropriate for Rosette to be dressed in a Santa themed dress.
Rosette wears what appears to be an old bag or potato sack for most of the duration of Episode 14: Invocation Rosette. Her clothes become shredded during the previous episode which explains the drastic change in attire.
Starting at Episode 20: Temptation and continuing up to Episode 23: The Noise, Rosette is pictured in a plain black dress with a matching veil and bow. However, she remains wearing the mark of her contract to Chrono.
In the Final Episode: Chrono, Rosette is seen in a simple, old fashioned pink-purple dress with her soul timepiece still around her neck.