Gold ring with emerald and Celtic knot

I found a gold ring with a Celtic knot pattern winding around the band and a tiny emerald set in the crown. I spotted it yesterday afternoon around 4pm near the entrance to Cardiff Castle on Castle Street. The ring is mid-sized and looks well-loved, with a small nick along the edge and an inside engraving that reads 'A.E.' It clearly seems sentimental, like it might belong to someone who wears it daily. If you know who this belongs to, email [email protected] and tell me where you lost it or describe the engraving so we can reunite it.