Katana/samurai swords?

if i were to buy a real japanese samurai or katana sword that say they are made in japan. (i know the fakes will say made in china lol.) but how can i tell the difference between the real and the fakes if they both have japanese symbols on them. are there curtain specs, like the curve in the blade, length, etc.
Update: dude im pretty sure the japanese makes some cheap fake ones.
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