There are at least two different printings of the English Z-Man edition. The first printing was done by Z-Man before the Z-Man/Filosofia merger, and these were printed in China, and use a linen-finish card. These will clearly say "Made in China" on the back of the box.
Later printings, including anything after the Z-Man/Filosofia merger, were done in Germany and use a rather flimsy Dominion-style cardstock with flat finish, and is in general a poorer quality playing card. These will indicate "Printed in Germany" on the back of the box.
Also, the Z-Man logo of the first printing is a white rectangle, and in the later printing, is just the letters.