Unsigned Vintage Rhinestone screw back earrings

These Vintage white Rhinestone screw back are a rare find, the craftsmanship of the fine costume jewelry of 1920's-1960's is shown in the design. I want to say these are from the 1940's . It is possible they are as early as the 1920's but could be as new as 1963. But most statement Earrings were clip-on by then. The screw back is adjustable. They are just a bit smaller than a quarter in size. Cleaning is easy as these do not tarnish easily. They have no markings and was probably part of a set.