A Civil War re-enactment.
More seriously, one such blue-gray blend is called periwinkle.
Lavender
It's a brown nut, with a grayish tint.
More of a brownish grayish color like cement but with a huge mixture of brown paint in it mixed all together.
brown
turquoise
brown
Just mix a bunch of colors and every time you mix three different colors together they'll make a grayish brown color
The color that red, yellow, and blue make, is black. Although I read in a book that red, yellow, and blue makes brown. Though that is not true. If that wasn't the color you wanted, I would try doing gray, mixing the color with red. (That would turn out to maybe brown,) If it still isn't brown, Then you are out of luck. Sorry! :(
cheese
purple or brown
When black and blue are mixed together they will make very dark blue. This is called a shade of blue. If you use mostly black you may not notice that there is blue in the color.
Brown
It all depends on the shades of brown and blue you are using, personally, my guess is that it would just be a bluish-brown color, and that might be useful in painting, although I looked online, and someone said that they mixed brown and cerulean blue and it made a type of green. It really just depends on the shade of the two colors. If you own paints, acrylic or watercolor, you could mix the two together and see if you add white or more blue or more brown, because typically, you don't get a specific color every time. You could use the whole white paint tube and get a grayish brown, or add red and get a purple- brown color, it just varies from there, I really think the question should be, "What wouldn't the colors brown and blue make in paint." Because there are various shades.