I recently got this golden ring because I liked it. However, someone brought to my attention that it looks as if it is made out of gold, which I do not believe . At a closer inspection I've noticed these marks inside the ring. The information I've found online are quite confusing and contradictory. I tried focusing my phone as clear as possible. It seems to be a CK and the number 58.
If anyone could help, I'd gladly appreciate it.