A wide number of collectable varieties exist across the Australian decimal coin series. One of the most popular varieties appears on a 50 cent piece from the year 2000. The coin was issued to celebrate the passing of the millennium and features on the reverse a stylised Australian flag, the word “Millennium,” and the denomination. On the proof version, the flag is pad-printed onto the coin in color, while the circulation issue has a non-colored flag that is designed into the dies and struck in the usual way.
It is on the circulation-issue coin where the variety exists, with examples featuring detailing that is either incused or in relief (raised). Specifically, the crosses of Saint George and Saint Patrick in the Union Jack are incused on the scarce variety, while the crosses are struck in relief on the standard issue. Less noticeably, but still noteworthy, are small differences in the way the surface of the Commonwealth star is presented: the star on the normal coin has a mottled appearance, while the surface of the star on the variety is smooth.
According to an article in The Journal of the Numismatic Association of Australia, the two pairs of dies that would strike the Incused Flag 50 Cent were specifically prepared for use on coinage for the annual mint set. However, for reasons not officially disclosed, coins struck from the normal in-relief dies were used in the sets instead, and the coins featuring the incused flag were released into circulation. What is not clear, however, is why a slightly modified design for the mint set coin was necessary in the first place. While the Royal Australian Mint has not released an official explanation, an anonymous informed source suggests that the design was going to incorporate colored enamel in the incused parts of the flag (a first for an Australian coin at the time). The result would have been a vibrantly colored Union Jack, similar to the pad-printed coin in the proof set.
The exact number of coins minted is not known, but the anonymous informed source estimates that 200,000 pieces were released into circulation, based on the number of dies used to manufacture them. In circulated grades, the coins trade for $50 to $100, while better examples sell for more. Mint State specimens are scarce, as none were preserved in the annual mint set and the variety was only identified in 2006; these can trade for over $1,000 in MS63 or better. Just one example has achieved PCGS MS65, which is the highest grade PCGS has currently awarded the variety. That particular coin can be considered a modern rarity.
To the decimal coin collector, the incused 50 cent piece continues to be one of Australia’s most popular varieties. Like the One Dollar Mule, the incused 50 cent was created under mysterious circumstances. However, unlike the mule, the collector has a very good chance of actually finding one in their change, keeping the numismatic spark alive.