Adele Simpson vintage jewelry was made in the 1940s through to the 1960s. The art deco elements you mention, would position your piece as being an earlier design.
Simpson's clothing (she was a fashion designer like Coco Chanel & Elsa Schiaparelli) and jewelry were only sold in upscale boutiques.
Simpson produced a limited amount of costume jewelry in the 1940s and 1950s to coordinate with her clothing designs, so it could be quite rare. Even then, her pieces were expensive for fashion jewelry, ranging from $50 to $500 per piece.
Adele Simpson Jewelry is know for its high quality and workmanship. Since it is so rare, most collectors buy whatever items they can find. The secondary market values are good and increasing.
