I also agree with the people saying this is 1980's to today. The
glued-in marcasites, widely spaced apart, the glued center stone in a
faux bezel, and textured back are characteristics of recent jewelry. Art
Deco period marcasite sterling has heat-se...
This site gives a lot of information about dating clasps and patents for
a few of them.
http://www.morninggloryantiques.com/JewelChatFindings.html The Farnham
clasp which is the patent you are showing is not just a roll-over clasp,
but the method of ...