17th Bn Cap Badge With Overlay
 

I have recently acquired a 17th Bn CEF badge with an overlay on it. The badge itself is marked "STER" on the back and is a heavy badge, but it also has an overlay over the central design of the badge. The overlay might be plated copper as there is a hint of copper colour in part of the crown. The badge itself looks like old dull silver, but the overlay is very shiny. I would say it is too shiny to be silver. I am wondering what the story is on the badge. Is it one that was used after 1918 for some time even though the "17th" designation would have ended. Also the lugs are made from flattened copper wire and I was wondering if this might set a possible date for the production of the badge. The "STER" is visible on the back of the Stag's forehead just above the brow, but does not show well in the photo. It is a nice badge, just a little too shiny to look right somehow. Was wondering if anyone had an idea of this badge's story.
Thank you
Don