Let's talk about Color...

[darkormex]

There is an oft-listed color variety that is a stamp's original color and the color black...For example, the very common French sower stamp, Scott 159, 5c Green, has a variety listed here: 

www.gpfs-online.org/france/fr/database.php?P=pLIJs7WCmraxue3DRm6%2Fv4WvJk8B8cToFEJP4VZAqKhPPZRxbNVYBROPVzrwBdZHx5rb5trBx7LA1MlrsZF83w%3D%3D

The color variety is Green-Black.  I have struggled for years to understand what the difference is between Green and Green-black or any other color variety that combines the original color with -black, such as Blue-black...etc...Can any of you provide an example of the difference or describe for me what the difference is between Green and Green-black? For many years I just thought it meant that the stamp was a darker shade variety.

[Butterfly]

Just a darker shade is all I know.
Here is a chart of the ISCC-NBS colors, which color labeling agencies seemingly totally ignore.
On the chart 152 blackish Green is VERY VERY dark and 157 green Black even darker!!

[darkormex]

Thank you Butterfly...this is useful...I will look for these colors online.