How old is my cameo and what is the name of the maker?

by Elaine
(United Kingdom)

I have a very beautiful cameo. It is in gold mount. The gold is marked with a star (Italy) then 50 this being the 'maker' but I cannot identify the maker number 50, followed by NA (Naples), followed by 378 (I think but difficult to see) which I think is the gold purity mark.

Is it true that shell cameos are only made in Torre de Graco?

With this information can you give me a date and the name of the maker?

Many thanks for your help in this matter

Elaine Sharp