LONDON (NYTIMES) - A tiny Leonardo da Vinci sketch sold on Thursday (July 8) at Christie's for £8.9 million (S$16.7 million) with fees, a record price for a Leonardo drawing at auction.

Leonardo's delicate silverpoint study, Head Of A Bear, measuring just under 7.6cm by 7.6cm, and thought to date from the early 1480s, was included in Christie's summer "Exceptional Sale" of high-value historical works of art assembled from a range of collecting categories.

Estimated to sell for £8 million to £12 million, the drawing was bought by a single bid from an as-yet-unidentified buyer in the auction room. There was no competition from any telephone or Internet bidders.

The final price of US$12.2 million (S$16.7 million) was marginally better than the US$11.5 million given in 2001 for Leonardo's slightly larger silverpoint study, Horse And Rider, the previous auction high for a drawing by the artist.

"These prices are absurd," said Mr Jean-Luc Baroni, a dealer in museum-quality old master drawings, based in London and Paris. Mr Baroni said that if he had been asked to price the work, he would have valued it at about US$2 million.

"You're buying a name. It's nothing to do with the love of drawings."

"Ok, it's a Leonardo. But it's so tiny," he said. "It's a postage stamp."

The drawing might have been small - it is about the size of a standard square Post-it note - but the sale on Thursday was viewed by many experts as possibly the last opportunity to buy an original Leonardo drawing from a private collection.

Prices for virtually any work associated with this most famous of Italian Renaissance artists have soared since the astounding US$450.3 million given in 2017 for the painting Salvator Mundi.

In June, Christie's sold a 17th-century copy of the Mona Lisa for €2.9 million (S$4.65 million).

On Thursday, just hours before Christie's sale of the drawing, Sotheby's sold what may well be a 20th-century copy of the Mona Lisa for £378,000 at a day auction of old masters. It had been estimated at £8,000 to £12,000.

"Leonardo is the magic name," said Mr Anthony Crichton-Stuart, director of the London dealership Agnews, who had been following Sotheby's day sale.

Leonardo was known to create "composite" animals in his art by combining elements from different species. Scholars have associated the drawing of a bear that sold on Thursday with the famously animated head of an ermine in Leonardo's celebrated Portrait Of Cecilia Gallerani, dating from about 1490, in the National Museum in Krakow, Poland.

"It was a very beautiful, very poetic drawing," said Mr Stephen Ongpin, a specialist dealer in old master drawings, based in London. "What I liked was the tenderness of the depiction. It's not like a scientific drawing. But it was small."

Mr Ongpin said that he thought Christie's valuation had been "correct", given that the estimate reflected a record price for a Leonardo drawing set 20 years ago.

Mr Ongpin and other dealers identified Christie's anonymous seller as American billionaire Thomas Kaplan, best known for his touring collection of paintings by Rembrandt.

Mr Kaplan acquired the drawing from London dealer Johnny van Haeften in 2008, as indicated in Christie's cataloguing. Mr Kaplan declined to confirm that his was the "family trust" making the sale.

Mr Ongpin said that Christie's had been looking for the "Salvator Mundi effect" by offering the drawing in its evening "Exceptional Sale", which appeals to wealthy collectors of trophy objects, rather than at a specialist old masters auction.

"There are one or two private collectors and one or two museums who could have bought a drawing like this," Mr Ongpin said. "But Christie's was also looking for a buyer who doesn't collect drawings and would be entranced by the name."