This portrait of Justine Gardner is another example of the strong impact that a limited palette of primary colors can achieve.
The key is using pure color and taking advantage of the inherent value of the local color. Yellow will never be a dark value. Reds and blues, used as pure undiluted pigments will never be as light a value as yellows and can be stretched from dark to mid-range with a bit of dilution.
Portrait of Justine drawn first with a black ink using a dip pen, followed by strokes of pure color allowed to mix wet-in-wet on the paper.