Like a very large Jupiter cuff bracelet bangle on your wrist?
Funny you mention Art Deco. Technically, Art Deco is the exact opposite of Art Nouveau.
Whereas Art Nouveau is about organic asymmetrical shapes and natural colours with natural materials, Art Deco came in the 1920s with highly geometric and symmetric shapes, in man made materials like brass, steel or aluminum, and if natural materials are used, they are "cold" materials such as marble and granite, preferably contrasting with metal accents. It's main subject is modernity. Think giant sky scrapers, internal combustion engine, electric and radio devices, and aluminum airplanes. Very Dieselpunk.
https://en.wikipedia.org/wiki/Art_Nouveauhttps://en.wikipedia.org/wiki/Art_DecoIn Steampunk there is always a balance between the technical and the artistic, and we're not afraid to combine historical periods, as that is the whole point of Steampunk. More than anything we are anachronists.
More modern technology like electric devices will meld with the highly geometric Art Deco. Older technology like gears and steam will meld with the older Neo Gothic and Romantic styles of the Victorian Era, which are also geometric, albeit different. But Art Nouveau sits right in between the two periods and is based on nature which is the subject of Sailor Jupiter, see?
But, pedantry aside, this discussion recalls the style used by Japanese manga studio CLAMP's xXx-Holic manga/anime series, where the animation is drawn in a style reminescent of Japanese wooden block print, and where the style is an equal mix of 1890s Art Nouveau and 1920s Art Deco.
https://en.wikipedia.org/wiki/XxxHolicTheir latest spinoff:
http://www.mangahere.co/manga/xxxholic_rei/Right click to zoom
Really interesting graphics, and the book manga is a work of art itself. It's difficult to see how you could meld these two disparate styles, but when drawn together with a Japanese print style it makes a lot of sense.
Perhaps give your character an edgier look with a Hime-princess look (Google Japanese term, but basically like a Flapper bob in the front, but with the hair on the back very long, like the main female character in xXxHolic - at the expense of recognizability because the original Sailor Moon characters are so... well, 1980s, shall we say?
Or perhaps not. Just make her with an all-short bob, closer to the 1920s styles. It looks to me that Sailor Jupiter is naturally tuned to a 1980s New-Wave short-bob look, vaguely related to the 1920s Flapper "wavy-bob" hair cut.
Somewhere between Art Nouveau and Art Deco, there is a congruence that will match your character's concept, though it's difficult to visualize now, TBH.
Perhaps I'm babbling to much

I tend to do that
JW