Please help identify 925 cup or beaker marked sunray PS 700

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This is a 3" tall silver julep cup or beaker. It tested with Schwerters as .925 or sterling silver. It is marked on the bottom with what looks like sunray or crown and the letters PS (or PG?) and 700. I have looked everywhere and can't find this mark. Can anyone help me identify the origin, maker and approximately when this was made? Thank you for your help!