The blue gene can and does express itself in various different shades of blue, some blues can be so dark that they appear black and it can express in the lightest shade of blue that you may think it was more a silvery color than blue. Blue is also a leaky gene and will allow leakage as you see in your birds that show a couple of random darker blue feathers on the body.
The blue gene acts like a diluter (not sure if diluter is even a word, but it works
) gene, one copy of the blue gene will dilute black to blue, 2 copies of the blue gene dilutes the blue even further to Splash that usually will express itself in a white color feather with random flecks of various shades of blue feathers through out the body of the bird. When a splash bird is placed next to a genetically white bird (such as a leghorn) the two colors that appear white will look completely different. The splash variety allow a person to best see the leaky traits of the blue gene with its random blue feathers.
I would say the first 2 birds are Blue Copper (the second being a very light blue) and the last bird I am also inclined to say is a blue, but , on the other hand if one of them was a splash it would be the last bird photo'd.
edited to add a photo of one of my splash Marans pullets and one of my blue Marans pullets, for me it is easier to see than to read.
I also tossed in a photo of a dark blue Marans pullet and my blue copper rooster that appears black so you can see how many shades the blue can express in
