The moral of the story is to never trust online color swatches to be accurate. Because I did all my window shopping online, and because my laptop screen is apparently brighter than most, I was under the impression that "Marine Blue" was actually a kind of cobalt. When we went to get Beverly fitted, there was indeed an example of the dress we wanted in that cobalt blue satin, which we assumed to be "Marine." The tags either did not specify, or did so in very fine print. We had it in our hands when the nice salesperson asked us what we had in mind, and we said we wanted that dress "in this blue." That was all well and good, but they didn't have her size on hand, and she had to try on a green one. Once her size had been determined, we actually ordered the dress in "Marine Blue", and so it was written in the paperwork.
Enough time passed for all four bridesmaids to order their dresses, and for two to actually receive them. I got my first look at what "Marine Blue" really was when Bev brought hers home. Rather than the lovely royal blue around which I had planned my decorations and flowers, what we had was an almost black, military uniform blue. Too late now.
I don't hate it, but it's not what I expected. However, if I had planned on a blue that dark, I would have gone with white accents instead of black. Oh, well. Hopefully it won't look too much like a funeral.