The Isleworth Mona Lisa is an early 16th-century oil on canvas painting depicting the same subject as Leonardo da Vinci's Mona Lisa, though with the subject (Lisa del Giocondo) depicted as being a younger age. The painting is thought to have been brought from Italy to England in the 1780s, and came into public view in 1913 when the English connoisseur Hugh Blaker acquired it shortly after it had been sold from Montacute House, where it was thought to have been hanging for over a century. The painting would eventually adopt its unofficial name of Isleworth Mona Lisa from Blaker's studio being in Isleworth, West London. Since the 1910s, experts in various fields, as well as the collectors who have acquired ownership of the painting, have asserted that the major elements of the painting are the work of Leonardo himself, as an earlier version of the Mona Lisa.: "Like Eyre and Pulitzer before them, the current owners of the Isleworth painting are convinced that it is in part by Leonardo".

In 1914, art critic Paul George Konody criticized early reports of the painting, which contained errors that he believed caused skepticism about the painting to become "hostile incredulity", but Konody nonetheless found that the painting was clearly "very largely worked up by the master himself".Paul George Konody, "Another 'Mona Lisa' Found in London?", The New York Times (15 February 1914), p. 25. Konody also found the painting to have features "far more pleasing and beautiful than in the Louvre version". A number of Italian experts in the 1920s echoed Konody's assessment of authorship by Leonardo at a time when the painting was more broadly examined. Much later authorities have made varying characterizations of the degree to which the painting can be ascribed to Leonardo; in 2012, The Guardian described the art world as being "split" over the question, and in 2013, Reuters said that it was "dismissed by some experts", but "also won support in the art world". Art historian Jean-Pierre Isbouts has endorsed Leonardo's involvement in painting the work, asserting that "24 of 27 recognised Leonardo scholars have agreed this is a Leonardo", while art historian Martin Kemp dismisses the proposition that Leonardo painted any part, and in 2012 described his contemporaries in the art world as being equivocal, or making "encouraging but noncommittal statements" on this point.: "The role-call of significant contemporary Leonardo specialists who openly and unequivocally supported the attribution in public was precisely zero. Alessandro Vezzosi, who spoke at the launch in Geneva, and Carlo Pedretti, the great Leonardo specialist, made encouraging but noncommittal statements about the picture being of high quality and worthy of further research".: "Even as Leonardo was perfecting the Mona Lisa, his followers and some of his students were making copies, perhaps with an occasional helping hand from the master. Some are very good, including those known as the Verono Mona Lisa and the Isleworth Mona Lisa, prompting claims that they may have been painted wholly or mostly by Leonardo, though most academic experts are skeptical".: In Marini's checklist, which he describes as: "Listed here are all paintings considered autograph works of Leonardo and works attributed to other artists in which it is possible to identify Leonardo's hand" the painting does not appear.: In Zöllner's catalogue, that he describes as: "The following catalogue raisonné contains the cartoons and paintings by Leonardo da Vinci's own hand, a number of early copies of his lost paintings and cartoons, together with more contentious attributions, insofar as these are rationally justified" the painting does not appear.: "Other copies of the Mona Lisa include the so-called Isleworth Mona Lisa, which some commentators asserted was Leonardo's first version of the famed portrait. The claim was a controversial one, with several leading Leonardo scholars flatly denying it".

Kemp and others who doubt Leonardo's hand in the painting attribute it to the Leonardeschi, Leonardo's workshop, believing it to be one of a number of copies of the Mona Lisa produced by Leonardo's collaborators, assistants, and pupils, though, as Leonardo biographer Walter Isaacson expressed it, "perhaps with an occasional helping hand from the master". In 2010, The Mona Lisa Foundation was founded to investigate if the Isleworth Mona Lisa was painted in part by Leonardo,: "The privately funded Zurich-based Mona Lisa foundation was created in 2010 with the intent of authenticating the painting and has continuously promoted the work".: "The foundation therefore concludes that Leonardo was responsible for the face and hands of the woman in the Isleworth picture, while an inferior artist must have painted the clumsy landscape in the background". but as an earlier version of the Louvre Mona Lisa.: "The purpose of the foundation is to investigate the evidence that Leonardo da Vinci painted two versions of the Mona Lisa portrait and to present the art history, scientific research and comparative studies of the earlier version of the portrait, historically referred to as the 'Isleworth Mona Lisa.

Differing views have been expressed on the relative weight to be given to scientific evidence versus connoisseurship. Physicist John F. Asmus, who pioneered laser-restoration techniques for Renaissance art, and who had previously examined the Mona Lisa in the Louvre for this purpose, published a computer image processing study in 1988 concluding that the brush strokes of the face in the painting were performed by the same artist responsible for the brush strokes of the face of the Mona Lisa in the Louvre,Asmus, John F. "Computer Studies of the Isleworth and Louvre Mona Lisas", in T. Russell Hsing and Andrew G. Tescher, Selected Papers on Visual Communication: Technology and Applications (SPIE Optical Engineering Press, 1990), pp. 652-656; reprinted from Optical Engineering, Vol. 28(7) (July 1989), pp. 800-804. and replicated that finding in a 2016 study. However, curator Luke Syson has argued that science is "only ever one of several factors we'd use to assess the authenticity and authorship of a work of art"., noting that "Syson does not accept that scientific evidence can conclusively settle debates over the authenticity of pictures such as the Isleworth Mona Lisa". An independent 2015 academic journal article also attributed the work to Leonardo on stylistic grounds.

Description

The Isleworth Mona Lisa is of the same subject as the Mona Lisa in the Louvre: "For the last four decades, a portrait of a woman closely resembling the subject of Leonardo da Vinci's famed Mona Lisa has remained under lock and key in a Swiss vault". and there are many similarities between the two. Both paintings depict a dark-haired woman, Lisa Gherardini, who sits at an angle and is surrounded by the landscape behind her. The work measures 84.5 × 64.5 cm, slightly larger than the Louvre Mona Lisa.: Chapter 3: Looking at Lisa However, the Isleworth Mona Lisa is differentiated by the model being noticeably younger,: "Except this woman is obviously much younger than the subject of the Louvre painting". having columns,: "She also appears flanked by columns that are absent from the artist’s renowned portrait". and being painted on canvas.: "One important concern voiced by a large number of art historians and connoisseurs relating to the Isleworth Mona Lisa is that Leonardo never painted on canvas but generally painted on wood". The canvas is of hand-woven linen cloth, characterized by "simple 'tabby' weaves with an average count of 18 threads per cm2 in the warp and 16 threads per cm2 in the weft, that cross one another regularly, with some variation in thickness. The result is a deformation in which the warp is slightly tighter than the weft".

Face and hands Konody observed of the Isleworth subject that "[t]he head is inclined at a different angle". Physicist John F. Asmus, who had previously examined the Mona Lisa in the Louvre and investigated other works by Leonardo, published a computer image processing study in 1988 concluding that the brush strokes of the face in the painting were performed by the same artist responsible for the brush strokes of the face of the Mona Lisa in the Louvre. Asmus found that the head appears to be "tilted forward toward the viewer ... consistent with the dramatically shorter appearing neck, which is also a greater angle to the vertical than that of the Louvre painting". Another early reviewer commented that "[t]he head is tilted more forward and the parting of the hair is exactly in the center, while that of the Louvre picture starts in the middle of the forehead and runs towards the back of the head at an impossible and incorrect angle"."English Picture May Be Original of 'Mona Lisa, Detroit Free Press (15 February 1914), p. 60. Asmus observed that "the Isleworth figure has a somewhat higher forehead, a slightly wider face, and less of a bulge in the veil over the proper left side of the head". He further reported that "the eyes are much wider set in the Isleworth painting". John Eyre reported Adolfo Venturi, in his early 1920s examination, praised "the beauty of the eye drawing ... is the principal portion done by Leonardo together with the line of the mouth".

A review of the painting in the Deseret News shortly after it was first shown to the public describes its tonality as being darker, and describes the coloring as being in "accordance with almost all the works attributed to Leonardo—that of a golden glow—while the finish is of a most minute character".Scott, E. L. "Yet Another "Mona Lisa" Adds to Mystery of Louvre Picture", Deseret News (14 February 1914), p. 25. Italian curator Lorenzo Cecconi, who also examined the painting in the 1920s, said that "the fusion of the tints of the flesh, especially in the eyes; the line which designs the nose, the mouth, and the oval of the face" were remarkable, and indicated that "this may be a second work of the Great Leonardo". In the same period, Renaissance scholar Arduino Colasanti thought "the upper part with the eyes and nose of the face" were definitely by Leonardo, and noted collector Ludovico Spiridon stated that "the face has been painted by Leonardo; no doubt of this at all". In the 1960s, the art dealer Henry F. Pulitzer argued that "densitometric tests on the planes of face and hands show a gradual change of tone values from dark to light which only [Leonardo] da Vinci, with his amazing eyesight, was capable of"."Not One, But Two Mona Lisas Indicate They're 'Twins, Arizona Republic (8 January 1963), p. 11. Asmus similarly found in the 1980s that amplitude histograms sorting the number of pixels of each brightness level in these features "reveal a remarkable similarity even though the images are noticeably different". Other differences have been observed with respect to aspects of the face: