This is an earlier necklace by Coro. I have seen this same design in a red pin, but never in a blue necklace. So I am guessing it is a rather rare design which is why I saved it! This design is heraldic with a crown, Maltese cross, blue enamel, rhinestones and pearls. The center section is riveted on and spins. The necklace is choker length at approx. 15 inches.
You can tell the necklace and pendant were well loved. There is quite a bit of wear to the gold plating on the necklace as well as areas of the pendant. There is also the remnants of a price sticker or something along those lines on the back. I did not want to risk removing it. Perhaps it might be worth replating, using as a placeholder for a set your working on, or you can enjoy wearing it instead of leaving it in your collection. If you added the pendant to a different necklace, that would also spruce it up quite a bit!
That being said, this is a very neat Coro design. The signature is script with no copyright, no angle etc. and per "Coro Jewelry A Collectors Guide" by Marcia "Sparkles Brown", it dates this piece to 1921-1945.