Australian Small SD and Tiny SD 5c
The reverse of the Australian 5c piece has changed in subtle ways on multiple occasions since its introduction in 1966. The exact reason for most of these changes has never been stated but it is likely the changes were in pursuit of improved die life.
One such change was first detected on a small number of 5c pieces in 2007 - the position of the echidna had changed slightly, as had the size of the designer's initials (SD) under the echidna. On the older type reverse there was a noticeable gap between the top of the echidna and the rim and the initials SD had curved tops and bottoms; on the newer type reverse the gap between the top of the echidna and the rim was much smaller and the initials SD had flatter tops and bottoms and were also smaller in general.
Examination of 5c pieces dated 2007 and onwards showed that the small SD/low echidna type was being replaced by the new tiny SD/high echidna type: clearly the Royal Australian Mint had a large reserve of 5c reverse dies though as the old design has been used from 2007 up to and including 2022. With the exception of 2007 the new design has been used to produce the majority of circulating 5c pieces, suggesting that the initial change occurred late in 2007.
| Year | Low Echidna | High Echidna | Number searched |
|---|---|---|---|
| 2007 | 90.07% | 9.93% | 292 |
| 2008 | 0% | 100% | 595 |
| 2009 | 11.55% | 88.45% | 407 |
| 2010 | 22.39% | 77.61% | 393 |
| 2011 | 0% | 100% | 294 |
| 2012 | 0.33% | 99.67% | 929 |
| 2013 | 0% | 100% | 608 |
| 2014 | 12.66% | 87.34% | 687 |
| 2015 | 0% | 100% | 226 |
| 2016 (plain) | 0% | 100% | 236 |
| 2016 (penny) | 0% | 100% | 18 |
| 2017 | 0% | 100% | 212 |
| 2018 | 0% | 100% | 254 |
| 2019 (IRB) | 0% | 100% | 218 |
| 2019 (JC) | 0% | 100% | 6 |
| 2020 | 0% | 100% | 267 |
| 2021 | 0% | 100% | 387 |
| 2022 | 0% | 100% | 73 |
While no small SD/low echidna coins are known in circulation for 2008, 2011, 2013, 2015, 2016, 2017, 2018 or 2019 (IRB), non-circulating examples are known to exist in various mint-produced sets for 2008, 2011, 2013, 2015, 2016 and 2019. The 2012 small SD/low echidna is also widely-thought to be a non-circulating coin but it has been detected in circulation in small quantities by the author. All commemorative 2016 5c pieces are believed to be tiny SD/high echidna too (including those in sets), but too few have been examined to be able to state this definitively. It is unclear if any JC obverse 2019, 2020 or 2021 5c pieces were struck with the small SD/low echidna at all as none have been sighted or reported: it is unlikely in any case. A small SD/low echidna 2022 5c piece has been reported in a mint set but no images have come to light.
It is likely that the anomalous 2014 small SD/low echidna is the last circulating example as, until it appeared, the variety's use on circulation coins had been declining and it had not been seen in circulation since 2010.