Cabinet cards

I recently came across a cache of cabinet cards in my father's garage. These are albumen prints which were popular from the 1870s to the end of the century. They replaced the earlier and much smaller carte de visite. They are all of family members from my Cornish ancestors. Unfortunately  I can only put names to a couple of them and, as I have no older relatives, I can't ask anyone else. I think this one is my great-grandmother (my grandfather's mother) as a young woman wearing a very elegant dress. I wonder what colour it was.