Eight solid navy in all weights, weaves, and configurations.
E.g., 8 oz. to 18 oz., SB, DB, 2 piece, 3 piece, flannel (both heavy and light), herringbone, serge, twill, and worsted.
Although navy is the building block of a man's wardrobe, I am coming around to Will's thinking that grey looks better as one's hair starts greying. See Will at http://asuitablewardrobe.dynend.com/2012/01/complement-your-coloring.html