I find it hard to believe that someone working in a fabric store wouldn't know they make navy thread. Where has she been? I have several different shades of Navy so yes they do make Navy thread. I think probably the reason they don't put the color on the end of the spool is that there is usually numerous shades of every color. I think there must be some code to the numbers, such as all browns start with the same number, blues with another number etc., but I've never paid attention to that.