Love to know what you have used for those skin tones. Great work.
Just my basic 'flesh' recipe/ Naples Yellow reddish + Burnt Umber + Burnt Sienna From there you can get to almost any skin-tone in existence. Darker like these + Burnt Umber,( you can actually go as dark as the darkest Senegalese, Zulus or Central Africans). Nordic= lighter + Naples Yellow, American Native & South American + Burnt Sienna. For Asians add a little Yellow Ochre.
Shading Burnt Umber, Lighter shading Burnt Umber + Burnt Sienna. Highlights Naples Yellow reddish.
Eyes Burnt Umber + Phtalo Blue. This gives you a dark bluish-green colour that actually looks darker than black but isn't.
Lower lips a little Cadmium Scarlet in the flesh mix.
Teeth, eyes, Titanium White mixed with Naples Yellow.
On some Europeans especially those in desert or tropical climates an little additional Alizarin Crimson in the hollow of the cheeks for added 'redness'
In a colder climate a little Phtalo Blue mixed in with the basic flesh mixture.
Except for the Phtalo Blue which is Winton, all Rembrandt Oil paint.