A life-size portrait of the Mughal emperor Jahangir, who reigned from 1605-1627, sold for £1.4m at Bonhams' Indian and Islamic Sale on April 6, slightly below its high end estimate.
The 1617 work, attributed to Abu'l Hasan, Nadir al-Zaman went to a Middle East museum, meaning investors have missed out on owning the wonderful piece for now.
Previously displayed at the National Portrait Gallery in 2010, the emperor is shown seated on a gold decorated throne holding a globe, wearing elaborate robes and jewellery.
The surrounding Persian inscription states it was painted at Mandu in 1617.
Alice Bailey, head of Indian and Islamic Art at Bonhams, commented: "This is one of the rarest and most desirable 17th century paintings ever to come to auction.
"There is no other work of its kind known and its importance cannot be underestimated."
She added that the extraordinary detail and complexity of the painting both fascinate and bewitch the beholder.
The auction's total sales came to £2.7m