A major problem the photography community faces is fake SD cards, which are much more common than you might think.

It can be tempting to find the cheapest SD card with the highest storage capacity that you can find. But the chances are, if you’re purchasing a high capacity SD card for a low price, it’s a fake. Fake SD cards are a bad investment, risky to use in your devices, and could cost you your data. They often come convincingly-branded with a well-known SD card manufacturer, like Samsung, SanDisk, Huawei and Kingston. Buying an SD card from an untrusted source is incredibly risky; the top culprits are eBay and Amazon Marketplace. But some SD card fakes are so realistic, there’s a chance you could end up buying one from a trusted retailer.

One reported way that fake SD cards enter the legitimate marketplace is through refunds. Scammers will buy a legit SD card from a reputable seller, typically online so they deal with a large volume of orders every week, and then return a fake SD card for a refund. The fake SD card will have been produced at a fraction of the cost, which is where the profit comes from. This fake product may then be unwittingly be sold to another customer, who may not be able to tell the difference until it breaks and their data is lost.

So how can you spot a fake SD card from a legitimate one? Fake SD cards will often come in poorly designed packaging, so make sure you examine it closely; try matching up the serial number on the box. When using a fake SD cards, there are several giveaways. A reduced read/write speed is incredibly common. You might buy an SD card with an advertised speed of 100 MB/second read/write speeds, but when you test it at home, you’re only getting speeds of 20 MB/second. Sometimes, older, legitimate SD cards with slower read/write speeds might be rebadged and sold with purported faster speeds. Another common giveaway is reduced capacity. This can be harder to identify, as the microchip responsible for reporting the amount of storage space available might be programmed to give a false reading; your machine might display 256GB or free space, but it could be a tenth of that in reality. These fakes are more convincing, and you’ll only realise when you’ve started to fill them up. Some fake SD cards have ridiculously unreal storage capacities, like 2TB. Again, the microchip may well be programmed to show that there is 2TB of free space available, and you won’t know until you start filling it up.

There are two ways you can protect yourself against fake SD cards. Firstly, you should try and buy from a smaller seller, who will typically spend more time examining returns; if fake SD cards are returned to them, it could severely impact their business. On the other hand, a large seller will typically pay less attention and fake SD cards could slip though. Secondly, test your SD card as soon as you purchase it. Connect it to your computer and paste a large file of several GB, and take note of the write speed. If it is significantly less than the advertised speed, you’ve probably got a fake SD card. You can also use software to test the read/write speed of your SD card – CrystalDiskMark is a great example of such a program. If you suspect your SD card has a smaller storage capacity than advertised, a program called H2Testw can examine your SD card and report back to you how much space there really is.