antique sterling box & locket tiffany portugal real or fake???

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I have a tiny sterling box with a small engraved locket,The box is marked STERLING PORTUGAL TIFFANY & CO .I can see it's old by the hinges,it is very plain .I contacted tiffany and asked questions but all I got was if I pay $100.00 they will tell me if it's authentic.I know tiffany had pieces made in Spain and I know there were fake pieces from Portugal but did they turn out any authentic peices in Portugal ?any info would be greatley appreciated thanks