Unfortunately, I am no expert and Juliana jewelry was of course never signed, but this accessory looks to be the real deal to me. I've seen verified Juliana pieces which greatly resemble this brooch, right down to the coloration.
Not 50, but rather two, shades of gray glass cabochons are enlivened by gleaming, light-catching aurora-borealis rhinestones. All stones are are prong-set, though some are open-backed while others are closed. Measurements are approx. 2" at widest point x 2 1/2" long. This beautiful pin is in extremely good to excellent vintage condition.