A ring can be made from different metals and can also have different gemstones.
Ring 1 can have different 'varieties' (Var):
Var 1: ring 1, metal 1, gemstone 1, gemstone 2
Var 2: ring 1, metal 2, gemstone 1, gemstone 2
Var 3: ring 1, metal 1, no gemstone
Var 4: ring 1, metal 2, no gemstone
Var...