After seeing thread after thread on this subject, I thought I'd cobble together a quick guide for people to determine whether they have a genuine or a fake Sony Memory Stick Pro Duo. Most of this information is available on other websites but has been condensed for easy digest. ;)
If you've recently bought a Sony High Speed 1GB or 2GB from eBay, the chances are it will be a fake. Stores in Hong Kong, China and Singapore are flooded with these things at the moment and it's actually a much harder task to find the genuine item! I actually ended up with a fake one myself from eBay, although in the end I managed to get mine returned for a refund. Notice how cheap they are, they sell for as low as $120/£70 in some cases. Either way if you buy from eBay - you have been warned!
It's also worth bearing in mind that even if you do have a fake Memory Stick, and it's still working after a few months then you should be okay. It may not be the real deal, but hell at least it still works! Which is more than can be said for some unlucky people out there..
Update! (14/1/2007) Thanks to Muratcan for this :
Things to Looks forOriginally Posted by muratcan
If you have bought a Sony 2GB High Speed Memory Stick Pro Duo, when you first format the card the available capacity should be 1,910 MB. Fake models have varying sizes, usually 1,948 MB or 1,949 MB. Some fake cards also use a trick to display the full capacity available but in fact can only store 1GB or thereabouts.
A genuine Sony product has superior quality packaging and should be properly heat-sealed around the edges. This is a tell tale sign. Also the quality of the ink on the card inside will show up a fake. Look at the black bit on the back, good quality printing from Sony will not have 'white dots'. Note: Even fake cards still carry the Sony hologram.
This is a genuine Sony card. Noticed how it is properly heat sealed around the edges.
A genuine example of a 1GB card.
A fake 512 MB card. Notice how the packaging is sealed with six crappy blobs of glue.
Fake 512 MB and 1 GB side by side.
Build quality, size and shape.
A fake Memory Stick may look the real deal at first sight, but if you compare it with a genuine item you can see the differences. The writing on a genuine card should be engraved into the plastic, not 'stuck' on. A fake stick may also be thicker in width that the real deal.
Can you tell the difference from these two 512 MB cards?
Notice how the fake card on the left is thicker than the real example on the right? This is the cause of many a card being jammed in a PSP. ;) Not all fake cards are that much thicker though. My one had no such problems in this area.