I love John Singer Sargent's work in general (as do almost all realist artists), and in particular his oil sketches of bedouins and arab people. This one ("Man With A White Turban," 1891) can be found on the Harvard Art Museums site.
My final ink test sketch before proceeding with a larger Abraham Lincoln portrait I have waiting. I like the color of this ink, but I think the Sepia works better on this paper and with the gouache highlights than this color ink (Red Earth).
Pen and ink (Daler-Rowney "Red Earth") with wash and gouache hightlights on Canson Mi-Tientes paper ("Sky Blue")