What shade of blue matches an orange comforter?

No shade of blue will match an orange. Orange and blue are opposites and will never match. If by "match" you mean compliment or "go with", then you get the shade of blue that is of the same intensity as the orange. For example, if you have a deep orange comforter, you may want to try a deep royal blue or even a bright navy; and if your orange is pale, bordering on the peach, you could try one of the pastel blues.