France Color Reference

I'm trying to find some way to distinguish shades on early France issues, especially Ceres, Napoleon III and Sage issues - not just inks but also papers (or underprints).
For example, how on Earth can I tell if my 1 centime stamp is olive green or bronze green? How can I tell if my stamp is on yellowish or straw?
I have color references for GB and US, but they're not much help here. I've searched but failed to find a similar product for France. Any tips welcome!

This is not an easy topic as you have found even before you get into the France or French colonies issues.
What catalogue are you using? A detailed catalogue such as Maury will help as there are many illustrations on the various plates and varieties listed.
I wouldn't bother too much about the Sage issue shades as I have 100's of the type II 5c green which I would say no two are the same shade.
The catalogue only lists major differences.
With used issues the paper is very hard to determine if it is aged, dirty etc but auction catalogues are useful here as you can find mint, certified examples to help you.

Anthony, thanks! That's helpful.
I am using Ceres and Scott (I live in the US). The latter is particularly unhelpful on color shades. I will look into picking up the Maury.
I did have an invitation from a woman I met at a stamp show to see her own specialized collection of France, which was very nice of her, though obviously I cannot take away her stamps to use as reference!

For the 1c Napoleon the difference is quite obvious and maybe not described that well in Scott for example.

Hmm. Thanks for posting that, Anthony! Still not sure I can tell the difference, though - is the bronze green the one on the left? On screen at least, it seems to be simply a darker shade of olive, rather than a different hue. Is there a metallic sheen to it? I can't tell. Sorry to be such a bother...

The paper is noticeably bluer on the olive.
I've just checked my Maury catalogue and they list 9 printings for this issue!