1931 W517 Strip Card Set

There are a lot of W517 counterfeit cards in circulation and for the untrained eye the reprints are quite convincing. The most common reprints have 'W517' printed on the bottom left corner, so if you see that, it's a guaranteed fake.  Also known as the 'Spigler' reprints, as these were produced by Jim Spigler. These were also issued in three card vertical strips. Of course, the scammers are likely to trim the bottoms off to remove the obvious sign, so it can often be a lot harder to tell if the borders are narrow.  Below are uncut reprint strips with the 'W517' in the bottom left corner. 

Here's a fake W517 Ruth that has been noticeably trimmed a bit extra where the 'W517 text should be.  This sort of cut should be a dead giveaway:

Of course, there are also known W517 full size counterfeits which DO NOT have the W517 text on the bottom.  The only true way to identify these reproductions is to get very high resolution scans or if you can look at the card in person, examine with a loupe.  Take a look at the light brown colored borders under magnification; if the cream color is made up of tiny dots of different colors (black, pink, yellow and blue), they are definitely fakes. And if it is real, the brown borders will only show brown dots.  In addition, the dots within the circle that contains the card number should be white without dots. 

The paper stock on the W517 fakes is also an important key to look out for.  The 'Spigler' reprints were made with a slightly whiter card stock, as you can see in the comparison of the back images below.  The differences are hard to tell with a naked eye, but the fakes have a brighter card stock which would flouresce under bright light;  the real cards have a darker greyish color and a thinner card stock.