Need Help Identifying Hallmark

by PearlGirl
(USA)

I recently purchased a ring that I believe may be of Russian origin. It appears to be made of yellow or light rose gold. I'm fairly certain that the stone is synthetic corundum laced with vanadium. It measures 13mm and appears to have been set upside down. Does anyone know why that would be?

The hallmark is stamped on the outside of the band and includes what appears to be the letter z, followed by a right-facing man's profile, followed by the number 56. I haven't been able to locate this exact hallmark. The closest one I've found is Russian (1906-1917) 14K gold.

I'm hopeful that someone can help me learn more about my beautiful ring. Any information would be most appreciated.

Thanks!