I tried to make what I thought was a simple change to colors.txt, giving the blues a lighter shade, but it turned my pond turtle shells from green to blue. Here's an image first with the standard color scheme, then using the blues from Vherid's Default+ color scheme:
I also tried using using the color values for cobalt and azure listed at
http://dwarffortresswiki.org/index.php/DF2014:Color, but with the same result. It turns out that only changing blue (as opposed to light blue) causes this issue.
I am using Mac version 40.24 with no mods; the only changes I've made are to options in init.txt and d_init.txt, and a personal tileset (not graphics set).
Something that might be related is mentioned under the Color Tokens section of this wiki page:
Material contaminants and dyes do not use color flags; instead, they reference color tokens defined in descriptor_color_standard.txt. Color tokens are simply referenced by the token name, e.g. [STATE_COLOR:SOLID:DARK_GREEN] or [POWDER_DYE:EMERALD]. However, the defined RGB values are never actually displayed in-game - instead, the game uses one of the above 16 colors, choosing the one with the closest RGB values.
Unfortunately, pond turtle shells use [STATE_COLOR:SOLID:DARK_GREEN]. So my question is this: Is there a way for me to lighten the blue shades in colors.txt without affecting the [STATE_COLOR:SOLID:DARK_GREEN] token? It doesn't have to be the exact shades I mentioned, I just find the standard blue to be too dark. My previous attempts changed blue from RGB 0-0-128 to 18-51-175 (Vherid's Default+), then 0-71-171 (Cobalt).
If that's not feasible, is there a way for me to alter the [STATE_COLOR:SOLID:DARK_GREEN] token directly so that it's not affected by changes to colors.txt? Or is there a third option that I'm not aware of? As long as I end up with lighter blues and green pond turtle shells, I'll be happy.