Are you certain it's not a fake? It seems to be lacking details and a bit crude looking. The As in Espana look especially wrong. I'm going to say fake. It's definitely not a 50 centimos coin, since the details and lettering are completely wrong. Sorry, but you likely don't have a coin worth much of anything.
It has the "look" of a shipwreck coin (wavy surfaces). Both A letters in "ESPANA" look wrong. I don't know how else to say this. They don't look like how they're supposed to look... I'm going to try to attach an image from NGC of an authentic one. All the detail on the obverse (face side) look muted, like someone made a copy of something else.
