Is It A Cup? - What Kind of Cup? - Sterling or Nickel Plated, Hand Tooled Cup ?

This is a hand made, hand tooled cup of some sort that I have owned for literally decades. I believe I found it at a flea market. It has no markings, and only shows some mild repair work to the bottom. A jeweler looked at it and wasn't certain if it was silver plate or nickel? The cup was formed by rolling out a sheet, cutting it, hand tooling the grape vines around it, then finishing out the form.

A very unusual item that neither the jewelers, antique dealers or knowledgeable friends have been able to identify. Can someone out there take a look and give me your opinion?

Thank you all for taking a look, and for sharing your knowledge and opinions.

Katherine Poole
Blue Stones and Daffodils