I'm pretty sure the only place where true moldavite can originate is somewhere in the area of the Czech Republic. A meteor landed there, and the heat from the impact melted local minerals, which blended together and resulted in moldavite. It's a fairly rare stone, since it can come from only one place on earth.
Maybe something similar could have happened in Brazil -- but would that really be moldavite? The local minerals would be different in South America than in Europe.
It could be one of three things: 1. True moldavite cut, set, or processed by workers in Brazil; 2. A mineral of similar origin to moldavite, but coming from Brazil instead; or 3. A hoax.
Those are my thoughts.