Color mixer

[Medium]

Ah! You don't want to blend with multiple preset colors in between, but using a different color model I suppose! The above looks like the blending was done in HSV or HSL space. (Don't know if right- or left-handed hue, but that should be simple enough to try out.) So instead of blending using RGB, just do it in HSV/HSL. That should get you pretty close to the above result.