Svetla Nikolova, who is from Bulgaria but lives in NY now, called the painting "spectacular".
'When Will You Marry?' by Paul Gauguin - the painter who was once Vincent Van Gogh's roommate at the iconic Yellow House in Arles, Provence - was speculated to be the most expensive painting sold privately by a Swiss art collector for $300 million.
The 500-year-old restored portrait of Christ was only recently rediscovered and was the last da Vinci left in private hands.
The painting of Christ was later recorded in a 1763 sale by Charles Herbert Sheffield, the illegitimate son of the Duke of Buckingham, who put it into auction following the sale of what is now Buckingham Palace to the king.
With at least six bidders and increments coming in at more than 15m, loud cheers broke out in the packed Christie's as the hammer came down.
The haunting image, entitled Salvator Mundi - or Saviour of the World - is now officially the world's most expensive painting, totally eclipsing nearest competitors by Pablo Picasso and Willem de Kooning. The opening price was $100 million and after 20 minutes of offers from phone-holding bidders in the NY auction room, the gavel came down at $400 million ($450.5 million including fees) and an unidentified buyer had won the fine-art prize.
Salvator Mundi's journey to becoming the world's most valuable painting was a long and unusual one.
The rare masterpiece by arguably the most important artist of all time was painted in the same time frame as the Mona Lisa, experts say. "Standing in front of that painting was a spiritual experience".
There was other big art-investment news during Christie's Post-War and Contemporary Art Evening Sale - notably Andy Warhol's Sixty Last Suppers, which went for $60,875,000. Da Vinci was born in the Republic of Florence, in present-day Italy, in 1452 and died in France in 1519.
"The idea for a group of works based on Leonardo's Renaissance masterpiece was proposed to Warhol in 1984 by Milan-based gallerist Alexander Iolas".
Altogether, Christie's big night pulled in a grand total of $785,942,250 (£597,220,555) - a pretty picture by any reckoning and a momentous occasion in the rarified world of fine art.