It appears that the 268 had a light green boiler for the Chicago Railroad fair. You can see the color just ahead of the cab in this photo.
[
eriksenphoto.smugmug.com]
But this was not the prototype or the norm while she was in service on the D&RGW--even when she got back to Salida the paint scheme was altered from what you see here.
Also look at this photo of the 494. Look at the different colors of black between the boiler and the domes. The boiler appears lighter and this may be what your seeing in the B&W photo--just two different shades of black.
[
eriksenphoto.smugmug.com]
Once agian I have to thank Steve for such wonderful photo's.
William
aka drgwk37