It was difficult to choose any one thing for the color purple. The Purple Heart comes to mind, as does any number of religious regalia. It is the color of royalty. At the end of the spectrum, it is a decidedly wintery hue. As Berg Polarbear requested, it is the color the sky turns right before the sun is fully set.

This in my mind makes purple almost a color of transition, as well. Perhaps fitting for moving on to a new piano?