I can find an Italian made piece that mentions an h superimposed over an s, but it also has the rest of the Italian hallmarks to go with it. The .750, the cartouche initials and number.
I would imagine the hs is the only marks on that one?
If it's only gold plated and cz's then I wouldn't spent too much time worrying about who made it. It's not any famous designer mark that I know of. Odd placement for it too. Could even be the clasp maker.