A recent object that passed through the lab was a black-and-white lithograph by the French Impressionist artists
Pierre-Auguste Renoir (1841-1919).
He's really famous for painting nudes.
The Large Bathers, 1887, Philadelphia Museum of Art
Other works you may recognize include:
Girls at the Piano, 1892, Musee d'Orsay
Luncheon of the Boating Party, 1880-1881, The Phillips Collection
I can't post any pictures of the lithograph I examined, but it is similar in style to these two (also, subject = mother and children).