There is often discussion about whether it is acceptable to mix brown and black or blue and black, but what about various shades of blue? Specifically, is it acceptable to mix navy and cobalt, or are they too close for comfort? I realize that just like a two toned piece of jewelry helps the wearer mix pieces in white and yellow metals in other places in the outfit, a top with mixed shades of blue can do the same, but I specifically have a number of either solid navy or cobalt or pieces with one of those colours as the primary background colour and wondered if I could mix them without looking ridiculous. Any photos to illustrate the point would help tremendously.