Cate, thank you for your input. I was leaning towards French too, due to the diamond shaped hallmark. I would really like to find out more in regards to the hallmarks/maker.
Rating
Stunning Art Nouveau Necklace! by: Cate
Tina
its gorgeous! The tiny little flowers that embellish the clasp look as if they are made from red gold? So chances are there are two colours of metals and two types of metals used in this piece. The maker's mark (although we can't clearly see what the letters read) nevertheless do look consistent with typical FRENCH maker's marks of the late 18th century. I would lean towards French Art Nouveau.
If you are an Art Nouveau collector you might be interested to know that it was the literary genius and contributions of an English poet in fact, William Morris (1834 -1896) born in Walthamstow, England who helped to establish the modern fantasty genre which we know today as the Art Nouveau.
http://en.wikipedia.org/wiki/William_Morris
Tina you have an eye for collecting - in my view, it would be money well spent to have this piece appraised.