Nike made the 2005/06 Arsenal Home shirt. This particular 'garnet' color itself was a good reason for Fakers to produce unauthorized copies of this shirt, but what made it unique is the fact that this shirt was the embodied celebration of the last season played by the Gunners at the historical Highbury Park.
This reason itself, alongside the fact that legends like Henry, Bergkamp, and Pires played for Arsenal at the time, is why this shirt has been produced by the fake-market for almost five years now. Ironically, the fake-makers failed to reproduce this exact shade of color, which looks much brighter than how it is in the original shirts.
Finally, another quick and easy way to spot a fake from the original is to take a look at Arsenal's crest. The Gunners' logo appears to be quite larger and deformed in the fake ones.