K, Shield, S.... Hallmark Can anyone tell me anything?

Hi Everyone!

Just thought I’d bring this piece to your attention. Can anyone tell me anything about this? Is it plate or sterling? It doesn’t have any of the sterling hallmarks I’m familiar with such as the lion passant, the anchor, etc.

Thank you everyone for your expertise. It is always much appreciated.
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I have this mark on a embossed chased European cityscape basket. I cannot find much information about this mark. Can anyone help?