Identifying Earring Maker's Marks: Understanding '1/20/ZKGF' and 'F' Hallmarks

Question
I recently picked up a pair of earring on a garage sale that had some dort of maker's mark on the. It says 1/20/ZKGF and there is a small circle with an F inside. Can you tell e anything more about this?

Answer
Hello Karen and thank you for your inquiry. Your earrings are gold-filled and the "F" hallmark is probably the manufacturer. Sometimes the makers didn't give much information in their markings and that makes it difficult to research. There are hundreds with just the F hallmark. Is there any other marking visible ? If so, we can go from there.