A glowing shimmering lucite feather hair barrette.

Vintage French - 1950s, maye 40s.

It's gently curved, and the stick only goes in one way, following the curve of the holes in the feather...to hold the hair securely.

The ones I have left have an odd surface mark - so cheaper !
I have them in either white or brown - the pin of the brown one is the same colour - just caught the light differently.