From the British Museum site:

“Painting; three quarter length portrait of Thayendanegea (Joseph Brant); wearing red and white feathered headdress with black headband ornamented with small silver rings; on his neck, he is wearing brown fur, which is tied with a bow at the right side. His red cloak with narrow, darker red stripes and brown fur collar is also decorated with silver rings. He wears a large white shell, an object of ritual significance to the Iroquois. An inscription in the top right-hand corner. Oil on canvas (framed and glazed)”

Gilbert Stuart (1755-1828) worked in Boston, New York City, London and Dublin.