Russian speaking master hallmark says "Миръ".
This should be a surname related to the place of Mir in Belarus (Grodno gubern) or a hallmark of the place of this name?
Any information known?
1) according to the forum rules you should embed your photos
2) your photos should be meaningful i.e. clear and sharp!
3) all the marks on your object should be shown
Your photos are not the best - the conditions for a serious assessment are not met.
I can se the number "12" - meaning 12 Loth silvercontent - also not Russia. I doubt that the letters are in Kyrillic - probably Latin = the maker.