A work on paper long dismissed as a fake Renoir has been reclassified as a genuine piece by the French Impressionist, Heidelberg University announced on 10 November. The sheet, once thought to be a forged pencil drawing, is in fact a hand-signed lithograph test print made around 1899, depicting the actor and singer Amélie Diéterle.

The reassessment began in 2023, when the sheet was offered to Professor Henry Keazor during a household clearance. Its owner had received it in the 1970s from the estate of a friend who owned a gallery, and a New York gallery had earlier judged it a forgery. Keazor, founder of the Heidelberg Forgery Study Collection, saw as soon as he unpacked it that it was a print rather than an original drawing, and set out with his students to place it among Renoir's known works.

The motif matched a known Renoir lithograph from "Germinal", an artists' portfolio published in 1899 in an edition of 100 copies alongside prints by Degas, van Gogh and Toulouse-Lautrec. But the sheet could not be one of those impressions: the portfolio copies carry a printed signature, while this one is signed by hand in black grease chalk. Under the microscope, the autotype paper revealed the outline Renoir had sketched for the two printing stones carrying the black and grey tones. Keazor's conclusion, confirmed by international specialists, is that the sheet is a proof pulled from only one of the two stones; because the signature sat on the second stone, Renoir signed it himself, making the proof a complete and valid work.

Such test prints are extremely rare in the art trade, Keazor said. The sheet will go on show in "Riddle around Renoir", a cabinet exhibition at Heidelberg's Kurpfälzisches Museum from 26 November to 21 March 2027, hung beside a forged Renoir drawing from the university's forgery collection. Afterwards, its previous owner will help decide where it is kept. The forgery collection, founded in 2021, holds about 140 fakes on permanent loan from police evidence rooms in Berlin, Bavaria and Baden-Württemberg, used to train students to spot forgeries.