Blogging can be helpful for finishing things, I know that pretty well ... but I'm surprised that this seems even to work for Jens! Because what I can show you today is Jens' still nameless piece. See that he added a pale, light grey-blue? It makes all the difference to me. Finding that colour was done with the help of the colour wheel.
Before Jens added that pale grey-blue, he found his piece was missing something. He wanted to add another colour, but was unsure which one to choose. I got my colourwheel, and we analyzed what was already there. The red looks like a dark red-orange; the gold we thought could be seen as a dark yellow-orange.
We flipped the colourwheel to the other side - see the yellow lines forming a triangle? The right name for this is triad - and it gave Jens his third colour: Cyan. As the first two colours were darkened, Jens picked a blue lightened with white for contrast. It works wonderfully!