This is a very, very unusual cameo (see all views, including back). The shell which gave birth to it had three distinct layers, and see what the carver coaxed from it - this lovely horse-within-horseshoe cameo.
It is Italian, signed, dating from mid-1980's. Just look at the fine carving on the mane, bridle, etc. Smashing! On back, the clasp is (hallmarked) "750", ie; 18 KG. It is of the type of safety catch one finds on bracelets. It is a good design and keeps the cameo pendant stable on your chain.
Pendant is 38 MM wide, widest point, and 40 MM height; 6 MM thickness.
Total shipping & insurance for this item be $8.00 or all USA shipments. For foreign shipments, inquire as to price vis a vis shipment method.