Stern produced the oil on canvas in 1942 when, at the height of her artistic abilities, she travelled to the Belgian Congo to seek inspiration for her craft.
The work depicts Emma Bakayishonga, the sister of the Watussi king Mutara III Rudahigwa, and is expected to achieve between £1m and £1.5m.
In her journal, Stern details her fascination for the painting's subject.
"She purses her lips as the Egyptians did," she writes.
"From beneath her long flowing robe her bare foot emerges. Never have I seen such beauty; it is like the black basalt foot of an Egyptian statue. It is expressive of a highly-bred cultured ancient race."
We think Bonhams' estimate looks slightly low, considering the popularity of the artist with high-net worth art collectors.
In March of this year Stern's Arab Priest sold for £3m at Bonhams in London, a record for the artist, while her Bahora Girl achieved £2.4m in 2010.
Giles Peppiatt, director of South African art at Bonhams, believes the "hugely powerful work" captures all Stern's signature strengths.
"The picture has not been seen for some […] years and so is fresh to the market," adds Peppiatt.
"It will doubtless attract a great deal of enthusiastic attention for South Africa's leading artist, and one of the top five women artists in the world."
You can find out how Watussi Woman fares later in the year, here at Paul Fraser Collectibles.
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