Can anyone tell me what this clip was used for?
Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
The clip you are showing is a "Dress Clip." They were used from the late 1920s into the 1950s - often in pairs, sometimes to change the necklines of dresses or gowns and sometimes just for decoration.
If you would like to learn more about them, there is some discussion of dress clips in Part III of this Jewelry Workshop:
https://forums.vintagefashionguild.org/threads/vintage-jewelry-workshop-part-iii.35686/