1. You will surely look dull and boring. 2. It is one of those unwritten rules in fashion that never match a darker colour with another darker colour if they are not the same colour. Meaning you can wear black over black or navy over navy but don't mix them. In my experience as a fashion image consultant and an entrepreneur for distribution of imported high end men's fashion for over 35 years, I still have to come across black and navy combination made fashionable, in all the fashion shows I attend internationally. I urge you to read fashion magazines like GQ and others, to follow the latest fashion trends. If you are serious about your dress sense, invest in attending fashion shows and get yourself a good image consultant to advise you on what or what not to wear, latest fashion trends, formal business dress, leisure and smart casual dress, personal grooming etc. Some image consultant will even go the extra mile by offering you services like: 1. Hooking you up with a nutrition