The 925 numeral is no hallmark only an indication put on by the manufacturer of the ring. No assay office has been involved to test the proclaimed silver standard. If the ring would have been officially assayed, the assay office should have marked the ring accordingly, see world hallmarks:
In the US the ring would have been marked by the maker with his maker’s mark and 925 and/or the word sterling.
Without an assay office mark and maker’s mark we will not be able to tell much more about the ring.