No marks that I can find, it is silver. I have been told you should never wash rhinestones, but I had to clean the silver...
C. '30s looks correct to me. If the rhinestones are not foiled, it is perfectly ok to wash them. If they are foiled, it is ok to clean them. Make sure that you do not leave cleaning solution on them, rinse well, and do not put them away or store them before they are totally dry. I clean vintage silver jewelry as minimally as possible but if the silver has tarnished to the point that it is black, I will wipe it off with a Sunshine Cloth. Some patina is not only acceptable it is desirable.
Agree with everything Linn said, and those are nicely constructed, with the additional columns of rhinestones on the sides. Pretty!
These very much resemble a pair I had, although mine had black glass stones. I was pretty sure that mine were 1930s and had a matching necklace. They are very very pretty!