N/A Vintage Green Marble Shamrock Cufflinks signed F

This is a vintage pair of gold-tone cufflinks with green marble, fronts with little golden shamrocks in the center. The pair have signs of use, but they are in otherwise great shape. The pair do have F stamp marks, but I am not sure who the maker is. Approximate Dimensions: 0.75 in. x 0.75 in.