Tried to date the ring but no luck(it doesn't look old), cant make out if its 1967,1917 or 1867... . I think the shield look like 1867 9k Birmingham gold ring. Didn't find the maker also :/
Hello Pavel, Afraid you are correct in thinking it's 'not very old' date letter is for 1992- no decimal point before the 375 indicates that it has to be later than 1975. I hope this helps. Kind regards Craig