A rare early colour image of Vincent van Gogh’s Six Sunflowers has been tracked down in Japan. It reveals that Van Gogh designed a bold orange frame for his still life. The framed painting, once in a private Japanese collection, was destroyed in an American bombing raid during the Second World War.

This newly discovered image is from a very scarce portfolio produced in Tokyo in 1921, which has escaped the attention of art historians. It is reproduced in The Sunflowers are Mine: The Story of Van Gogh’s Masterpiece, by Martin Bailey, to be published by Frances Lincoln on 5 September.

Van Gogh’s narrow wooden frame was painted in orange, producing a dramatic effect when set against the blue background of the still life. This reflects Van Gogh’s love of complementary colours (such as orange and blue), which have a vibrant effect when placed next to each other. Van Gogh has also varied the orange, so that it is a deep orange where it is next to the blue background and a lighter orange next to the lilac table.

We can now see how Van Gogh wanted to present his Six Sunflowers: the yellow-ochre sunflowers were set against a rich royal blue background and then framed in orange. This framing would have been revolutionary in 1888, when pictures were traditionally hung in gilt frames or, for very modern works, in white frames.

While researching my book on Van Gogh’s Sunflowers I was astonished to find that the artist’s self-mutilation had been reported soon after it happened in a Parisian newspaper. It appeared in Le Petit Journal on 26 December 1888, three days after Van Gogh slashed off the lower part of his left ear, following a row with Gauguin. Until recently, only one short newspaper report of the mutilation was known, which was published a few days later in an Arles weekly, Le Forum Républicain.

The newly discovered article in a Parisian daily records important details. Le Petit Journal reported that Van Gogh used a razor. He then went to a “house of ill repute”, where he “gave his ear in a folded piece of paper” to the doorkeeper. Van Gogh told the recipient: “Take it, it will be useful”. These baffling words suggest that Van Gogh must have been suffering from an acute mental problem throughout the night, and did not just slice off part of his ear in a passing moment of madness.

The Parisian report is also important in another sense. Van Gogh’s self-mutilation was the first item of provincial news in Le Petit Journal, so the article must have attracted considerable attention in the capital. It would have been seen by many of his friends and much discussed in the Paris bars that Van Gogh frequented. This must have only added to the distress of his brother Theo, who was a respectable figure running an art gallery.

It seems astonishing that a virtually unknown individual living over 600km away who mutilated himself would have warranted this attention in a four-page Parisian newspaper (taking a quarter of the space devoted to provincial news that day). But even then, there was something sensationalist about the ear incident which grabbed public attention.

• Van Gogh completed his original four paintings of Sunflowers in less than a week, twice as fast as has been assumed. He chose to depict sunflowers because the weather was bad and his models failed to show up. 
• There is also a second “unknown” Sunflowers painting which has always been hidden away in private collections. This is Van Gogh’s Three Sunflowers, with a bright turquoise background. It has never been exhibited in living memory and its whereabouts have been a mystery. Bailey reveals that Three Sunflowers was acquired by the Swiss-based Greek shipping tycoon George Embiricos, who sold it in the late 1990s. It was then bought by the present owner, a very discreet collector with a taste for Van Gogh.