Coin Collecting Advice: Spotting Valuable Errors and Varieties: A Guide

The transition to decimal currency in 1966 opened a new chapter for Australian collectors. While most coins that leave the Royal Australian Mint are perfect examples of precision engineering, occasionally, a mistake slips through. These errors and varieties can transform an ordinary piece of pocket change into a highly valuable treasure.

In 2026, as we celebrate the 60th anniversary of decimal currency, interest in these "minting mishaps" is strong. There are livestreams and YouTube channels and more dedicated to finding mishaps.

Understanding the Difference: Error vs. Variety

Before you begin your search, it is important to distinguish between an error and a variety.

• Mint Errors: These are accidental, one-off occurrences during the minting process. Examples include a coin struck on the wrong metal blank (planchet) or a "clipped" coin where the metal was cut incorrectly.

• Varieties: These occur when a specific die, the stamp used to create the coin, has a unique characteristic or a slight mistake. Because the same die is used to strike thousands of coins, varieties are found in larger numbers than unique errors.

Notable Modern Varieties to Watch For

Some of the most famous Australian varieties are subtle but command significant premiums.

• The 1966 "Wavy 2" 20-Cent Piece: On this rare variety, the horizontal baseline of the "2" has a distinct upward wave. This occurred on a small number of dies used at the London Mint.

• The 2000 $1/10c "Mule": A famous mistake where the "heads" side of a 10-cent coin was paired with the "tails" side of a $1 coin. The result is a $1 coin with a noticeably double-rimmed edge.

• The 2000 Millennium 50-Cent "Incused Flag": While the standard 50-cent coin has a raised design, this rare variety features a Union Jack on the Australian flag that is sunken (incused) into the coin.

Common Minting Mistakes

If you are "noodling" through your change, keep an eye out for these physical anomalies:

• Cuds: A "cud" is a raised lump of metal on the surface of the coin caused by a piece of the die breaking off. You might find these on the feathers of a lyrebird or the legs of a kangaroo.

• Rotated Dies: This happens when one of the dies is not aligned correctly, causing the "heads" and "tails" sides to be at different angles when the coin is flipped.

• Strike-Throughs: These occur when a foreign object, such as a piece of grit or grease, gets between the die and the coin during striking, leaving an indentation or a "blurry" section on the design.

How to Inspect Your Coins

Identifying these errors requires a keen eye and a bit of patience. Use a 10x magnifying loupe to inspect the fine details of the date and the rim. Look for anything that deviates from the standard design. Even a tiny "spew roo" (a small die crack on a $1 coin that looks like a line coming from a kangaroo's mouth) can add value to an otherwise common coin.

At Mint Coin Shop, we focus on providing pristine, uncirculated coins directly from the mint at RRP.

While we don't deal in "error hunting" ourselves, we appreciate the dedication it takes to spot these rarities.

Building a collection of standard releases at RRP is the perfect baseline for any collector, whether you eventually find a rare error in your change or not.

Good luck hunting for mistakes. It's a a fun hobby that engages many.