So that '7680' is almost certainly a jeweler's pattern or stock number, not a purity mark. Antique rings from 1890-1920 often had these inside the band along with the actual karat mark.
Look again very closely for a tiny 10K, 14K, 18K, or 585/750 near it. The emerald being bezel set and diamonds prong set with visible bases sounds like a late Victorian / Edwardian era ring, likely 14k or 18k gold.
If you can share a photo of the full hallmark area I can help narrow down the maker.
