It could be Aur Cymru, which was an exclusive makers mark by the company Welshgoldplc, which operated the Gwynfyndd mine in Wales up to 1998. However, if it is a genuine ring from this company it would also have hallmarks, the date mark and either be marked 375 for 9ct or 750 for 18ct. If none of these marks appear it will not be a genuine use of the exclusive AC mark. I hope this helps Brian
