Help identifying some jewellery

[Scarlett30]

Hi everyone, hope this the right place to post this. I received some exquisite pieces of jewellery as inheritance from my grandmother. My grandmother was Australian and I'm in England. Through many many hours of research I found one piece, sold by 5 dealers (from house clearances)in America. So I'm leaning towards them being American. All these pieces bare the same hallmark, which is really hard to make out. I think it's either an n or z with a circle. All the pieces are 14 k gold with mother of pearl inlay and gems. Any clues anyone can give towards age or designer would be amazing. Thank you for your help.