Ok great---I would LOVE to see pictures of them. So you may have answered what color the parents were too!! I do have a pair of columbian cochins but my birchens are in the pen too. So I don't know exactly where he/she came from.
A true coloumbian shouldnt be that dard and have that much color and a silver partridge shouldnt be that light. To me it looks more like what you would get when you cross Columbians with laced or partridge birds.