2007 $1 Selectively Gold Plated Subscription Coin, 1732 One Johanna. The original Johanna was a Portuguese and Brazilian coin struck between 1722 and 1733. A gold coin weighing 28.68 grams, it circulated throughout the entire world, being produced during the reign of John V of Portugal. The Johanna's signifcance in Australia's numismatic history was established in 1800, thanks to Governor Philip Gidley King. The Johanna was the highest denomination coin of the Procolamtion series, being valued at four pounds. This coin released by the Royal Australian Mint has been struck in Fine Silver, then gold plated to replicate the appearance of the original gold coin. Certificate of Authenticity is included with this coin numbered 2279. This coin was produced to demand with only 6949 being made.