Help Identify France 1960 Airmail - Mystere 20

Hi All,

Was sorting and posting some France Airmails and came across one that has a color variation.
It is a France 1965 Mystere 20 2.00 F. (Scott # C41)
On most of the examples I have the jet is a dark blue, but in this one the jet is brown/black. I did not see a listing in the Scott catalog for this variety. Also on this one, the blue is really blue, but on my other examples, the blue has a bit of greenish tint.
If anyone can provide some insight to this "Mystery", I would appreciate it very much.
In the scan, the one on the bottom is the one in question with the brown/black jet.

Thanks,
Dave N.

Lot of stamps from theses years in france have been produced in huge number and have a lot of variation of colours. None of them have been referenced in catalog. By the way it is still collectable, especially the major colour differences ;)

I would say that is sun bleached.
There is a 'uncolore' variety listed where every thing is blue.

Here are some of the variations that are possible from the earlier 1960 issue