Aside from the Australian 50 cent and $1 coins the 20 cent is the only other circulation coin that you will find with a different reverse to the standard issue*. The obverse of the 20c has the usual portrait of Queen Elizabeth II, the Arnold Machin portrait from 1966 to 1984, the Raphael Maklouf portrait from 1985 to 1998, and the Ian Rank-Broadley from 1999 to present. The reverse of the standard issue pictures a swimming platypus designed by Stuart Devlin.
Like the values of Australian 50 cent coins the values of Australian 20 cent coins is largely dependent on the condition of the coin. Very few coins you might find in circulation will be worth anything more than 20 cents. I’ll take a look at the standard issues before I cover the rarer varieties you could keep an eye out for.
The Australian 20 cent was only produced with the standard platypus reverse until 1995 when a smallish issue of 4.8 million coins was issued with a reverse commemorating the 50th anniversary of the United Nations. In 2001 another issue was released commemorating the life of Don Bradman. 2001 was also the Centenary of Australian Federation and nine 20 cent coins with different reverses were released celebrating this. Coins were released for New South Wales, the ACT, Queensland, Victoria, Norfolk Island, the Northern Territory, Western Australia, South Australia, and Tasmania. Most of these coins had an issue of 2 million coins, for some reason the Queensland and South Australian coins had a mintage of 2.3 million. Interestingly the reverse designs of the coins were the result of student design competitions in the schools of the respective states and territories of each coin.
2003 saw the release of a 20 cent celebrating the Year of the Volunteer (7.5 million minted), and 2005 a coin commemorating the 60th anniversary of World War II (32 million minted). In 2007, for the first time, there was a unique 20c issued in the uncirculated mint set (the Year of the Lifesaver), the same coin was also issued in a PNC. 2008 saw the cynical release of the two coin uncirculated coin sets by the RAM in addition to the normal uncirculated coin sets. This two coin set contains a unique 20 cent (the Year of Planet Earth) and the exercise was continued in 2009 with the Year of Astronomy 20 cent in the uncirculated two coin set.
Of the commemorative 20 cent coins mentioned above the United Nations, Bradman, and Centenary of Federation coins, if found in circulation may fetch a dollar or two each on Ebay. Truly uncirculated examples will get a dollar or two more. Catalogue values for each of these coins is only $6-$7 in uncirculated condition. The 2003 Volunteers and 2005 World War II 20 cent are worth face value, this is despite of how infrequently they show up in your pocket change. The mint set only coins, will very rarely (if ever) be found in circulation. The only real way of getting them is by getting a mint set and cutting them out of the set. Sometimes you’ll see individual coins available on Ebay because some people break up the mint sets to sell the coins and try to make a profit. Expect to pay $10-15 for one of them, and to receive about the same amount if you sell one.
In the next part of this entry I’ll cover some rare varieties of the 20 cent you can look out for in your pocket change that are worth a tidy sum.
*At the time of writing. Update July 2013. There have now been $2 coins with commemorative reverse designs issued.