Single vintage earring

Hello I’ve just rediscovered this lovely earring, I used to buy items like this as scrap, but had a idea of putting it on a chain and selling it as a pendant, first impression is it is vintage but I don’t know how old, remember reading that this style of hook goes back to Deco days but I could be wrong, now I’m looking at stones, this one looks very interesting and is quite big. Wondering if it’s fake because it looks like could be something different. Really don’t know where to begin looking for something similar