The Theater District’s newest club may not be over the top, but its designer does confess that the club is slightly over the rainbow. Emerald, located in the recently opened Revere Boston Common hotel, is a 6,000-square-foot lounge that is not intended to be a boisterous dance club — or a hotel lobby bar — but a stand-alone entity for sophisticated sipping designed by a firm out of Miami. It’s slated to open next week. We spoke to Emerald designer Amy Jakubowski from the firm BBG-BBGM about the transformation.