I believe it is a thermal plastic they used in the late 50's. It is a cobalt blue in color with gold tone setting and will compliment any French cuff shirt or blouse. Both men and women could wear this set. It is in good condition with a maker’s mark of Hickok. Overall oval size is 5/8" x 3/8”.
All my cufflinks and jewelry are sold in used, pre-owned condition. Vintage and Antique items by nature have some wear, imperfections and signs of use and age.
Hickok Cobalt Blue Faux Stone Gold Tone Cufflinks Cuff Links