Gold signet ring with emerald, found in Plymouth

I found a gold signet ring this afternoon around 3:40pm near the Mayflower Steps on the Barbican in Plymouth, Devon. It's a 14k gold signet with a small emerald bezel on top and a brushed finish along the band. Inside, there's a tiny engraving that looks like 'J.R.' The ring is in good condition, a bit warm from being in my pocket all day. If the owner can describe the engraving or the inside mark, or the approximate size, I’ll happily arrange a meetup to return it.