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It's a piece by F.Lli Magrino Argentieri In Firenze and retailed by Birks.
See: https://www.925-1000.com/forum/viewtopi ... 71#p126233
What you have is a resin base covered with a layer of silver. To identify such pieces and so that they are not to be confused with solid silver items, as they do contain a full set of Italian marks, the Italian government required some extra marks to be struck. These extra marks are a 'R' within a square, this stands for 'Riempito' (filled), and also a set of figures that indicate the amount of silver applied, in grams (1÷2 g, 2÷3 g, 3÷5g, etc.). These are not exact weights, but must fit into range stated by each mark, in this case, between 3 and 5 grams are applied.
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