Ronnie & Johnny – Searching for the Blue

This song is really about being obsessed by something until it takes over your life.
In this instance inspired by stories from people who fossick and dig for gems, who told yarns of how they would see some colour and would always want to dig a little more and then a little more.
It would become such a focus that all else paled in comparison.  Ronnie feels this can happen with anything that absorbs you, even playing music and writing songs!
So while the song is about a particular character, it can reflect many types of obsession.