Using black and purple, the focus of this theme is a great fountain surrounded by oversized rhinestones. Art deco fans atop purple columns covered with deep purple Mylar curtain scream elegance. Make diamonds out of holographic paper and hang them from the ceiling or scatter them around the stage. Behind the stage, build a huge art deco fan with holographic accents. Add black and deep purple gossamer.
Stars are such a great theme.
Consider a metallic star arch kit at the door an easily made prop that you can buy. Mylar stars floating on the ceiling, large stars center table under the centerpiece, an archway covered with stars for your photo opportunity and lots of star sprays here, there and everywhere. Hang star banners from the ceiling and add star cloud clusters with latex balloons covered with stars coming from above. You may also want to add a fabulous moonwalk bridge lit with candles for a great photo opportunity. This is a great theme and there is so much available to execute it.