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I am impressed at the speed of the responses (thank you). In regards to the possibility of the wheel being a Sheffield rose. The image detail is unfortunately more poor than I'd like. I had to put my cell phone camera (Zeiss pure view 41 mega pixel) to one of the eye pieces of my Zeiss 1896 Greenoug...

I received this a few years ago as a gift from my mother. There is no provenance attached to it. Given it has a lobster claw, spring loaded clasp (and that it appears to be original to the piece) I doubt it could be anymore than 40 years old. In searching the website and forums I couldn't ascertain ...