WHAT may appear to be small change could, in fact, turn out to be a small fortune - if you know what to look for. One rare 50p coin featuring a cartoon boy fetched £320 at auction online earlier this year. It's no secret that rare coins can fetch significant sums thanks to unique errors, low mintage numbers, or distinct features. The coin in question was designed for the 2012 London Olympics as part of a Blue Peter competition. The winning design was created by Florence Jackson, a 9-year-old from Bristol, in 2009. Her depiction of a high jumper mid-flight was selected from an impressive 17,000 entries. Coin enthusiasts have long been on the hunt for The Royal Mint's Olympic 50ps. Most of these coins were released into circulation in 2011, just before the 2012 Olympic Games in London. There are 29 different designs to collect, each showcasing a different Olympic sport, such as Taekwondo, Wheelchair Rugby, Gymnastics, Cycling, Boxing, and Archery. What makes this specific Blue Peter coin, recently sold at auction, particularly special is its rarity. While over 2.2 million Blue Peter coins, also known as Athletics 50ps, were issued, the majority were minted in 2011. These 2011-dated coins, though popular among collectors, typically aren't worth much more than their face value. However, the coin that fetched £320 on eBay in January is one of just 20,000 minted in 2009, making it an exceptionally rare find. CHECK IF YOU HAVE A RARE COIN Rare coins and valuable notes can be worth tens of thousands of times their face value. But sometimes it's just tiny differences which make them so lucrative. The most valuable coins tend to be ones with low mintage numbers or an error. Those qualities typically make them valuable to collectors. Your next step would be to check if your coin is still available to purchase in superior Brilliant Uncirculated quality from an official Royal Mint distributor, according to Change Checker. Certified Brilliant Uncirculated coins have been specially struck to a superior unblemished quality which set them apart from the coins you may find in pockets. SELLING YOUR RARE COINS There are many different factors to consider when trying to value a coin, including its condition and mintage, so it's important to do your homework first. If you've got a coin that you would like to sell at auction, you can contact The Royal Mint's Collectors Service. It has a team of experts who can help you to authenticate and value your coin. You'll need to enquire via email, and a member of the valuation team will contact get back to you. Take a picture of your coin and attach this to the email - you can find the details on The Royal Mint's website. Be aware that you will be charged for this service though - the cost will vary depending on the size of your collection. If you are looking to buy a coin online through a marketplace such as eBay, it's important to know exactly what you are purchasing. This is because anyone can list a coin on eBay and charge whatever amount they wish. You should also be wary of fakes online - and keep in mind that on eBay a buyer could pull out, which means the coin won't have sold for the price it says it has. Meanwhile, we have put together a guide on the rarest and most valuable coins. We also tell you what you should do if you find a lucky penny in your pocket.