France - Pre-Cancelled Sower Colours

Both Yvert and Scott list this issue as 10c ultramarine only.
Yet in these two pre-cancels the difference between deep ultramarine and light ultramarine is so obvious that it begs the question: Why is it just listed as simply "ultramarine" with no differentiation?
Isn't the colour difference definitive enough?
Does anyone here have a Gibbons' France? Thanks in advance.

Tony-

The surcharge on the right is pretty clearly type "r" from Yvert. Do you think the surcharge on the left is type "r" as well? I don't see a type "p" listed for this stamp in Yvert, but yours looks a little skinny in places for a type "r" (though admittedly a little fat in other places for a type "p").

How does it look in person?

Collin

You know, Collin, a few minutes before your note came in I was having a wonderful argument with myself about just your point.
And the answer I come up with is: I don't know. As you say, at one point it is and at another it isn't.
To me, it looks just as thick but not as dark.
My main interest though is the colour of the stamps - definitely different ultramarines and should be listed as such in my humble opinion.

How can we be sure this is not a 'changeling' from one cause or another. The3 lighter one seems to be faded, including the precancel marking.

I have a 2000-01 Cérès and a 2006-07 Dallay and both of those list your 10c precancel without shades. I don't have a newer copy since the two merged, but in these older editions, the Dallay definitely has more detail in their listings. I hope the newer Maury catalogue didn't stick with the Cérès layout.

Ryan

My examples on hand,
I only have SG simplified so cannot discriminate.
The top middle looks deep blue, some of the others are lighter
even to a violet type blue, sort of a "chalky" blue.
Anyway, yours for a bo-peep.