Ring Hallmark - pics attached

Hey, I have an unusual silver ring (pretty sure it is sterling silver, which I think is approx 40 years old (it has been passed down to me), just wondered if anyone could help me with the hallmarks (I have found nothing on the internet).

It has a cross indented, and also has a quater-circle shape, which I think has a 13 or B inside it, and next to this shape is a G. Not sure what these mean, but if anyone can help that would be brilliant! There are no other hallmarks on the ring, so do either of these suggest what specification of silver it is? Thank you!
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Well the short answer is i dont know… but… the marks do look Eastern to me. Perhaps Egyptian, not Persian, Or far Eastern. If you have other pix of the ring or better pix of the hallmarks i might be able to venture a better guess.

picture 2 -. looks like the netherlands