In TNG 3x24 "Menage a Troi" (and perhaps a great many other episodes; this is just the one I happen to be watching at the time I noticed) Wesley Crusher's communicator badge appears to be all silver, lacking the gold that is present in all the other commbadges, until he first appears in uniform.
While it is logical to speculate that this is because Wesley is an acting ensign, is there ever a canonical explanation, or any production notes that explain why this is so?