"The Fields," now on display in London, is a masterpiece valued at more than $34 million, the Telegraph reported Tuesday.
The work is said to have been painted 19 days before the 37-year-old artist shot himself in the chest.
"Here is an artist literally on the verge of taking his life and filled with tremendous despondency, yet he is still painting with lemon yellows, azure blues and emerald greens," said David Norman, of Sotheby's. "We know this is a man barely holding on to his will to live, yet he is able to separate his energy and focus on what he sees before him."
The picture is one of the last van Gogh works to be privately owned.
In a letter to his brother, Theo, van Gogh described three recent paintings, noting, "They are vast fields of wheat under troubled skies, and I did not need to go out of my way to try to express sadness and extreme loneliness."
Theo van Gogh refused to sell "The Fields" in his lifetime.