Does your comment refers to the question about the bubbles? If so: The question about the bubbles is often posed to determine authenticity: Cast copies have bubbles, too. But these bubbles are soft and can be perforated by a needle for example. "real" zinc" bubbles are hard and can't be perforated. Or at least not easily.
The badge looks authentic but zinc badges are neither rare nor very desirable (in my opinion). Especially because of the re-nazification, which represents a very serious damage/ repair, I would recommend you to pass on that badge.