Beautiful cat eye sunglasses, no marks.. 50's or 60's?

[Robin of Frocksley]

I'm thinking 50's (they're pretty narrow and small, which might be why I think they're older?), and have no idea how to describe the lovely shape of the arms. No identifying marks anywhere. The top through middle of the lenses have a bright mirror effect, the bottoms are slightly darker. They're pretty narrow and small, which might be why I think they're older? Thanks!