Genuine artifact from the wreck of the Sacramento sunk in 1668 of Salvador, Brazil.  The wreck was partially salvaged in 70s after being discovered by fishermen in about 130 feet of water.  Coin is from John IV (1640-56) and has been countermarked to 250 Reis under Alfonso VI (1656-67).  Coin was minted in Lisbon and is silver weighing 4.5 grams.  Great historic find.

Old Portuguese Shipwreck Coin