Vintage Sterling Vermeil Butterfly Earrings

These unusual butterfly earrings are a bit of a mystery to me.  They are solid sterling silver with a gold coating (vermeil).  They are labelled Handmade Sterling and Sterling and have a type of clip that I have not seen before.  Each butterfly has slightly raised wings for a 3D effect and cutout for the design on the wings.  I am guessing they are European and possibly from the 1940's when many of the gold over sterling pieces were made due to war rationing of other metals.

In great vintage condition with just a little bit of the vermeil plating loss.