This ring that I found recently in dry beach sand is made of very brassy-looking metal (I haven't tried to polish it yet), but there is an almost decipherable hallmark. My first impression on finding it was that it was low-carat gold, but on closer inspection it seemed too tarnished, especially since it was recovered well above the tide line. Also, there's a silvery surface on the metal in the area of the stones, which makes me think it's just costume jewellery, rather than precious metal. Experienced opinions would be welcomed.
