A gentleman's hosiery is becoming more and more an accessory rather than simply a necessary part of the wardrobe. Traditionally hosiery should match the trouser color and shade. Recently, a style trend has emerged that adds more color to the sock that ties it in with the rest of the wardrobe.
A purple argyle sock with a navy blue suit and purple shirt and tie for example. License is now being given to expand to colorful patterns and even prints in socks. Experiment and have fun if you don't have to be super conservative.