Hi Have you considered the well known and well established Australian jewelry firm of Angus & Coote (A&C)? Formed in 1895, still going to this day, well known especially for their wedding and engagement rings. The above statement is not with any guarantee, but it was my first reaction on se...
It might perhaps concentrate our minds if you were to tell us where your grandmother lived. She lived in the UK, and emigrated to Australia early 60s, but was married in the 30s or 40s. There was some speculation the ring was given to her from a previous generation, but the metric gold percentages ...
The A&C mark appears to be from silversmiths Asprey and Co, but I can't work out when they used this logo, rather than "A&Co". I don't even know how to describe the first marking, other than a mushroom cloud, but none of the hallmark searches come up with anything for that. I don't...