I have an apparently gold man's wedding ring, quite old, with a shamrock symbol and the letter A inside. I believe it to be my grandfather's wedding ring, from 1912. What can someone tell me about it's manufacture and where it might have been sold.

Attributing an origin and maker to an item without an image is extremely difficult. Single initial maker marks are hard to attribute since it could signify a great many manufacturers or none at all. You describe it as a gold wedding band with a shamrock design. Is the ring also marked with the karat quality of the ring? Are there any other marks on the inside to help us further? The manufacturer could be one of a thousand different jewelers who custom made a wedding band for your grandfather. I am sorry we cannot be of further help to solve your mystery.

Fred