Need Information On France Airmail Overprint

Does anyone know how to tell the real from the forgery on Frances C1 and C2 airpost stamps?

Here's some information on how to tell if you have a forgery:

http://www.richnoddystamps.co.uk/fo...ris-airmail/

22crows-------thanks for that excellent source .

Opinions wanted. The C1 looks ok and has the guidelines of 22crows information. By the way thanks and great site. But the C2 looks like it will not pass.

I am not an expert on these, but they look an awful lot like some of the overprints of the Dutch East Indies, which also have been faked quite extensively. I was looking at both stamps earlier and was going to ask about the second one. The first one looks authentic, but the second one?
The one thing catching my eye was the position of the plane over the wording underneath. Now, after reading 22crows' webpage I can see a whole flock of problems, like shape of the wheels, dot of the I and so on. Enlargement of the stamp shows many more problems!

Peter

So I have the stamps in hand and the C1 is fine but like I suspected the C2 is a forgery and is actually a Kull stamp. So here is my dilemma I received a great deal as I was bidding on the real one in the auction lot. A refund would be offered for the C2 for $30. How many think a C2 forgery would be worth that. I am actually considering keeping it even though it is not real because of the low cost. Would you do the same?

Had to amend the wording , it was a bit confusing.

If you ask the question 'What would some have to gain from forging these?' it is obvious that a 400% increase in value from the regular stamp is attractive and easy to do.
Even Scott mentions that excellent counterfeits exist so only a certificate could eliminate most doubt.

I would say of those are fakes - 'the tail wheel should be between the t and e of Poste'

I would keep them for reference but not at $30. The regular 2f Merson is easily available and it is virtually valueless as it is.