Members of the media take photos as a Sotheby's staff poses for a photograph with Banksy's 'Devolved Parliament' which has an estimated value of 1.5-2 million British pounds in a forthcoming sale in London, Britain September 27, 2019. REUTERS/Simon Dawson

Sotheby's staff pose for a photograph with David Hockney's 'Bridlington Studio Interior' which has an estimated value of 900,000 to 1.2 million British pounds ahead of a forthcoming sale London, Britain September 27, 2019. REUTERS/Simon Dawson

Sotheby's staff pose for a photograph with Banksy's 'Devolved Parliament' which has an estimated value of 1.5-2 million British pounds in a forthcoming sale in London, Britain September 27, 2019. REUTERS/Simon Dawson

Members of the media take photos as a Sotheby's staff poses for a photograph with Banksy's 'Devolved Parliament' which has an estimated value of 1.5-2 million British pounds in a forthcoming sale in London, Britain September 27, 2019. REUTERS/Simon Dawson

Members of the media take photos as a Sotheby's staff poses for a photograph with Banksy's 'Devolved Parliament' which has an estimated value of 1.5-2 million British pounds in a forthcoming sale in London, Britain September 27, 2019. REUTERS/Simon Dawson

Members of the media take photos as a Sotheby's staff poses for a photograph with Banksy's 'Devolved Parliament' which has an estimated value of 1.5-2 million British pounds in a forthcoming sale in London, Britain September 27, 2019. REUTERS/Simon Dawson

Members of the media take photos as a Sotheby's staff poses for a photograph with Banksy's 'Devolved Parliament' which has an estimated value of 1.5-2 million British pounds in a forthcoming sale in London, Britain September 27, 2019. REUTERS/Simon Dawson

Sotheby's staff remove ladders after posing for a photograph with Banksy's 'Devolved Parliament' which has an estimated value of 1.5-2 million British pounds ahead of forthcoming sale in London, Britain September 27, 2019. REUTERS/Simon Dawson

Presidential Commission on Good Government (PCGG) officials inspect some of the confiscated jewellery collection of former Philippine first lady Imelda Marcos during the appraisal by Sotheby's inside the Central Bank headquarters in Manila November 27, 2015. REUTERS/Erik De Castro

A Presidential Commission on Good Government (PCGG) official displays some of the confiscated jewellery collection of former Philippine first lady Imelda Marcos during the appraisal by Sotheby's inside the Central Bank headquarters in Manila November 27, 2015. REUTERS/Erik De Castro

A Presidential Commission on Good Government (PCGG) official shows a piece of jewellery from the confiscated jewellery collection of former Philippine first lady Imelda Marcos, during the appraisal by Sotheby's, inside the Central Bank headquarters in Manila November 27, 2015. REUTERS/Erik De Castro TPX IMAGES OF THE DAY

A Presidential Commission on Good Government (PCGG) official shows a pink diamond of the confiscated jewellery collection of former Philippine first lady Imelda Marcos during the appraisal by Sotheby's inside the Central Bank headquarters in Manila November 27, 2015. REUTERS/Erik De Castro

An appraiser from Sotheby's examines a pink diamond of former Philippine first lady Imelda Marcos during the Presidential Commission on Good Government (PCGG) appraisal of the confiscated jewellery collection from the Marcos family in 1986, inside the Central Bank headquarters in Manila November 27, 2015. REUTERS/Erik De Castro

An appraiser from Sotheby's examines a piece of jewellery of former Philippine first lady Imelda Marcos during the Presidential Commission on Good Government (PCGG) appraisal of the confiscated jewellery collection from the Marcos family in 1986, inside the Central Bank headquarters in Manila November 27, 2015. REUTERS/Erik De Castro

A Presidential Commission on Good Government (PCGG) official shows a jewellery set of the confiscated jewellery collection of former Philippine first lady Imelda Marcos during the appraisal by Sotheby's inside the Central Bank headquarters in Manila November 27, 2015. REUTERS/Erik De Castro

Appraisers from Sotheby's examine a piece of jewellery of former Philippine first lady Imelda Marcos during the Presidential Commission on Good Government (PCGG) appraisal of the confiscated jewellery collection from the Marcos family in 1986, inside the Central Bank headquarters in Manila November 27, 2015. REUTERS/Erik De Castro

A Presidential Commission on Good Government (PCGG) official shows a jewellery set from the confiscated jewellery collection of former Philippine first lady Imelda Marcos, during an appraisal by Sotheby's inside the Central Bank headquarters in Manila November 27, 2015. REUTERS/Erik De Castro

An appraiser from Sotheby's examines a piece of jewellery of former Philippine first lady Imelda Marcos, during the Presidential Commission on Good Government (PCGG) appraisal of the confiscated jewellery collection from the Marcos family in 1986, inside the Central Bank headquarters in Manila November 27, 2015. REUTERS/Erik De Castro TPX IMAGES OF THE DAY

Cast members of the ABBA inspired musical "Bjorn Again" pose at a grand piano made by Georg Bolin and used by the Swedish pop group ABBA to recorded many of their hit songs, at Sotheby's auction house in London, Britain, August 27, 2015. The piano is expected to earn $927,000-1.24 million (600,000-800,000 British pounds) when it is auctioned later this month in London on September 29. REUTERS/Suzanne Plunkett

Cast members of the ABBA inspired musical "Bjorn Again" perform at a grand piano made by Georg Bolin and used by the Swedish pop group ABBA to recorded many of their hit songs, at Sotheby's auction house in London, Britain, August 27, 2015. The piano is expected to earn $927,000-1.24 million (600,000-800,000 British pounds) when it is auctioned later this month in London on September 29. REUTERS/Suzanne Plunkett

Cast members of the ABBA inspired musical "Bjorn Again" look at a grand piano made by Georg Bolin and used by the Swedish pop group ABBA to recorded many of their hit songs, at Sotheby's auction house in London, Britain, August 27, 2015. The piano is expected to earn $927,000-1.24 million (600,000-800,000 British pounds) when it is auctioned later this month in London on September 29. REUTERS/Suzanne Plunkett

A cast member of the ABBA inspired musical "Bjorn Again" plays a grand piano made by Georg Bolin and used by the Swedish pop group ABBA to recorded many of their hit songs, at Sotheby's auction house in London, Britain, August 27, 2015. The piano is expected to earn $927,000-1.24 million (600,000-800,000 British pounds) when it is auctioned later this month in London on September 29. REUTERS/Suzanne Plunkett

A cast member of the ABBA inspired musical "Bjorn Again" plays a grand piano made by Georg Bolin and used by the Swedish pop group ABBA to recorded many of their hit songs, at Sotheby's auction house in London, Britain, August 27, 2015. The piano is expected to earn $927,000-1.24 million (600,000-800,000 British pounds) when it is auctioned later this month in London on September 29. REUTERS/Suzanne Plunkett

A Sotheby's employee poses with "Two Studies For Self-Portrait", painted by Francis Bacon, at Sotheby's preview in London January 28, 2015. The art piece is expected to fetch between 13 and 18 million pounds ($19.8 and $27.3 million) at the upcoming Contemporary Art Evening Auction in London on February 10, according to Sotheby's. REUTERS/Stefan Wermuth (BRITAIN - Tags: ENTERTAINMENT SOCIETY)

A model shows a 26.27-carat fancy brown-yellow diamond, diamond and conch pearl "Ballerina Butterfly" brooch during a Sotheby's preview in Hong Kong September 18, 2014. Designed by fine jewellery artist Cindy Chao and actress Sarah Jessica Parker to benefit the New York City Ballet, the item is expected to fetch between $750,000 and $950,000 at the auction house's Autumn Sale in Hong Kong on October 7, 2014. REUTERS/Bobby Yip (CHINA)

US-American violist David Aaron Carpenter holds the Macdonald viola by Antonio Stradivari, made in 1719, at Sotheby's gallery in New York, March 27, 2014. A rare Stradivari viola, considered to be one of the finest in existence, is expected to fetch more than $45 million in a sealed bids sale this spring, which would set a world record for the most expensive musical instrument ever sold. The 'MacDonald' Viola, made by the famed Italian artisan Antonio Stradivari in 1719, is the first to be on the market in 50 years, according to Sotheby's auction house. REUTERS/Eduardo Munoz (UNITED STATES - Tags: SOCIETY)

Violist David Aaron Carpenter of the U.S. holds the 'Macdonald' Viola by Antonio Stradivari, made in 1719, at Sotheby's gallery in New York March 27, 2014. The 'Macdonald' Viola, a rare Stradivari viola considered to be one of the finest in existence, is expected to fetch more than $45 million in a sealed bids sale this spring, which would set a world record for the most expensive musical instrument ever sold. The viola is the first to be on the market in 50 years, according to Sotheby's auction house. REUTERS/Eduardo Munoz (UNITED STATES - Tags: ENTERTAINMENT SOCIETY)

The 'Macdonald' Viola by Antonio Stradivari, made in 1719, is seen at Sotheby's gallery in New York, March 27, 2014. The 'Macdonald' Viola, a rare Stradivari viola considered to be one of the finest in existence, is expected to fetch more than $45 million in a sealed bids sale this spring, which would set a world record for the most expensive musical instrument ever sold. The viola is the first to be on the market in 50 years, according to Sotheby's auction house. REUTERS/Eduardo Munoz (UNITED STATES - Tags: ENTERTAINMENT)

Violist David Aaron Carpenter of the U.S. speaks to the media after playing the 'Macdonald' Viola by Antonio Stradivari, made in 1719, at Sotheby's gallery in New York March 27, 2014. The 'Macdonald' Viola, a rare Stradivari viola considered to be one of the finest in existence, is expected to fetch more than $45 million in a sealed bids sale this spring, which would set a world record for the most expensive musical instrument ever sold. The viola is the first to be on the market in 50 years, according to Sotheby's auction house. REUTERS/Eduardo Munoz (UNITED STATES - Tags: ENTERTAINMENT SOCIETY)

Violist David Aaron Carpenter of the U.S. plays the 'Macdonald' Viola by Antonio Stradivari, made in 1719, at Sotheby's gallery in New York March 27, 2014. The 'Macdonald' Viola, a rare Stradivari viola considered to be one of the finest in existence, is expected to fetch more than $45 million in a sealed bids sale this spring, which would set a world record for the most expensive musical instrument ever sold. The viola is the first to be on the market in 50 years, according to Sotheby's auction house. REUTERS/Eduardo Munoz (UNITED STATES - Tags: ENTERTAINMENT SOCIETY)

Violist David Aaron Carpenter of the U.S. plays the 'Macdonald' Viola by Antonio Stradivari, made in 1719, at Sotheby's gallery in New York March 27, 2014. The 'Macdonald' Viola, a rare Stradivari viola considered to be one of the finest in existence, is expected to fetch more than $45 million in a sealed bids sale this spring, which would set a world record for the most expensive musical instrument ever sold. The viola is the first to be on the market in 50 years, according to Sotheby's auction house. REUTERS/Eduardo Munoz (UNITED STATES - Tags: ENTERTAINMENT SOCIETY)

Violist David Aaron Carpenter of the U.S. plays the 'Macdonald' Viola by Antonio Stradivari, made in 1719, at Sotheby's gallery in New York March 27, 2014. The 'Macdonald' Viola, a rare Stradivari viola considered to be one of the finest in existence, is expected to fetch more than $45 million in a sealed bids sale this spring, which would set a world record for the most expensive musical instrument ever sold. The viola is the first to be on the market in 50 years, according to Sotheby's auction house. REUTERS/Eduardo Munoz (UNITED STATES - Tags: ENTERTAINMENT SOCIETY)

Violist David Aaron Carpenter of the U.S. holds the 'Macdonald' Viola by Antonio Stradivari, made in 1719, at Sotheby's gallery in New York March 27, 2014. The 'Macdonald' Viola, a rare Stradivari viola considered to be one of the finest in existence, is expected to fetch more than $45 million in a sealed bids sale this spring, which would set a world record for the most expensive musical instrument ever sold. The viola is the first to be on the market in 50 years, according to Sotheby's auction house. REUTERS/Eduardo Munoz (UNITED STATES - Tags: ENTERTAINMENT SOCIETY)

Violist David Aaron Carpenter of the U.S. plays the 'Macdonald' Viola by Antonio Stradivari, made in 1719, at Sotheby's gallery in New York March 27, 2014. The 'Macdonald' Viola, a rare Stradivari viola considered to be one of the finest in existence, is expected to fetch more than $45 million in a sealed bids sale this spring, which would set a world record for the most expensive musical instrument ever sold. The viola is the first to be on the market in 50 years, according to Sotheby's auction house. REUTERS/Eduardo Munoz (UNITED STATES - Tags: ENTERTAINMENT SOCIETY)

A Sotheby's employee poses for a photograph with an Imperial silver-gilt and cloisonne enamel icon of Christ Pantocrator which has an estimated value of £180,000 ($287,000) to £250,000 ($398,000) at Sotheby's in London, November 23, 2012. The Russian art sale will take place in London on Novemeber 26, and November 27, 2012. REUTERS/Stefan Wermuth (BRITAIN - Tags: ENTERTAINMENT SOCIETY)

A Sotheby's employee poses for a photograph with Ivan Aivazovsky's 'Moonrise over the Golden Horn' which has an estimated value of £700,000 ($1.115 million) to £900,000 ($1.434 million) at Sotheby's in London, November 23, 2012. The Russian art sale will take place in London on Novemeber 26, and November 27, 2012. REUTERS/Stefan Wermuth (BRITAIN - Tags: ENTERTAINMENT SOCIETY)

A Sotheby's employee poses for a photograph with Vasily Vasilievich Vereshchagin's 'Transportation of the Wounded' which has an estimated value of £800,000 ($1.275 million) to £1,200,000 ($1.913 million) at Sotheby's in London, November 23, 2012. The Russian art sale will take place in London on Novemeber 26, and November 27, 2012. REUTERS/Stefan Wermuth (BRITAIN - Tags: ENTERTAINMENT SOCIETY)

A Sotheby's employee poses for a photograph with Vasily Vasilievich Vereshchagin's 'Transportation of the Wounded' which has an estimated value of £800,000 ($1.275 million) to £1,200,000 ($1.913 million) at Sotheby's in London, November 23, 2012. The Russian art sale will take place in London on Novemeber 26, and November 27, 2012. REUTERS/Stefan Wermuth (BRITAIN - Tags: ENTERTAINMENT SOCIETY)

A guard stands by Salvador Dali's painting "Printemps Necrophilique", part of a collection of impressionist and modern art, to be auctioned off May 2, at Sotheby's auction house in New York City, New York April 27, 2012. REUTERS/Lee Celano (UNITED STATES - Tags: SOCIETY)

A girl looks at Edvard Munch's painting "The Scream", part of a collection of impressionist and modern art, to be auctioned off May 2, at Sotheby's auction house in New York City, New York April 27, 2012. REUTERS/Lee Celano (UNITED STATES - Tags: SOCIETY)

Visitors look at paintings, bronze sculptures, and furniture which are on display at Sotheby's in Paris October 21, 2011. The auction will be held in Paris October 26 and 27. REUTERS/Charles Platiau (FRANCE - Tags: SOCIETY)

The sculpture "Daphnis et Chloe" by French sculptor Jean-Baptiste Carpeaux, with an estimated auction value of between 1,000,000 ? and 1,500,000 ?, is displayed at Sotheby's in Paris October 21, 2011. The auction will be held in Paris October 26 and 27. REUTERS/Charles Platiau (FRANCE - Tags: SOCIETY)

A Sotheby's employee poses with artist Pablo Picasso's "La Lecture" in front of Marc Chagall's "David" (L) and "Bathsabee" (R) at Sotheby's auction house in London January 31, 2011. The Picasso is expected to fetch up to £18 million ($27.85 million) when it comes to auction as part of Sotheby's sale of Impressionist and Modern Art on February 8, 2011 in London. The Chagall's are estimated to fetch up to £3.5 million ($5.55 million) each when they come to auction as part of the "Looking Closely" private collection sale on February 10, 2011. REUTERS/Luke MacGregor (BRITAIN - Tags: BUSINESS SOCIETY)

A Sotheby's employee poses with artist Pablo Picasso's "La Lecture" in front of Marc Chagall's "David" (L) and "Bathsabee" (R) at Sotheby's auction house in London January 31, 2011. The Picasso is expected to fetch up to £18 million ($27.85 million) when it comes to auction as part of Sotheby's sale of Impressionist and Modern Art on February 8, 2011 in London. The Chagall's are estimated to fetch up to £3.5 million ($5.55 million) each when they come to auction as part of the "Looking Closely" private collection sale on February 10, 2011. REUTERS/Luke MacGregor (BRITAIN - Tags: SOCIETY BUSINESS)

A Sotheby's employee poses with artist Pablo Picasso's "La Lecture" in front of Franz Gertsch painting "Luciano" at Sotheby's auction house in London January 31, 2011. The Picasso is expected to fetch up to £18 million ($27.85 million) when it comes to auction as part of Sotheby's sale of Impressionist and Modern Art on February 8, 2011 in London. The Gertsch is estimated to raise £700 000 ($1.09 million) when it is auctioned as part of the Contemporary Art sale in London on February 15, 2011. REUTERS/Luke MacGregor (BRITAIN - Tags: BUSINESS SOCIETY)

Auctioneer Henry Wyndham (L-at podium) takes bids on the painting "Christ Carrying the Cross" by Alessandro di Mariano Filipepi, known as Sandro Botticelli and Studio, shown on a screen during Sotheby's Important Old Masters Paintings sale in New York, January 27, 2011. REUTERS/Mike Segar (UNITED STATES - Tags: ENTERTAINMENT SOCIETY)

The painting "Christ Carrying the Cross" by Alessandro di Mariano Filipepi, known as Sandro Botticelli and Studio, is shown on a screen during Sotheby's Important Old Masters Paintings sale in New York, January 27, 2011. REUTERS/Mike Segar (UNITED STATES - Tags: ENTERTAINMENT SOCIETY)

Auctioneer Henry Wyndham (L-at podium) takes bids on the painting "The Resurrection" by Alessandro di Mariano Filipepi, known as Sandro Botticelli and Studio, shown on a screen during Sotheby's Important Old Masters Paintings sale in New York, January 27, 2011. REUTERS/Mike Segar (UNITED STATES - Tags: ENTERTAINMENT SOCIETY)

A bidder looks at a catalog showing Tiziano Vecellio's (known as Titian) painting "A Sacra Conversazione: The Madonna and Child With Saints Luke and Catherine of Alexandria" during Sotheby's Important Old Masters Paintings sale in New York, January 27, 2011. The painting sold for $15,000,000. REUTERS/Mike Segar (UNITED STATES - Tags: ENTERTAINMENT SOCIETY)

Auctioneer Henry Wyndham (L, at podium) takes bids on the painting "Christ Carrying the Cross" by Alessandro di Mariano Filipepi, known as Sandro Botticelli and Studio, shown on a screen, during Sotheby's Important Old Masters Paintings sale in New York, January 27, 2011. REUTERS/Mike Segar (UNITED STATES - Tags: ENTERTAINMENT SOCIETY)

The painting "The Resurrection" by Alessandro di Mariano Filipepi, known as Sandro Botticelli and Studio, is seen on a screen during Sotheby's Important Old Masters Paintings sale in New York, January 27, 2011. REUTERS/Mike Segar (UNITED STATES - Tags: ENTERTAINMENT SOCIETY)

Auctioneer Henry Wyndham (L, at podium) takes bids on Titian's (formally known as Tiziano Vecellio) painting "The Madonna and Child With Saints Luke and Catherine of Alexandria" during Sotheby's Important Old Masters Paintings sale in New York, January 27, 2011. The painting sold for $15,000,000. REUTERS/Mike Segar (UNITED STATES - Tags: ENTERTAINMENT SOCIETY)

Auctioneer Henry Wyndham takes bids during Sotheby's Important Old Masters Paintings sale in New York, January 27, 2011. REUTERS/Mike Segar (UNITED STATES - Tags: SOCIETY ENTERTAINMENT)

An image of Claude-Joseph Vernet's "A Grand View Of The Sea Shore Enriched With Buildings, Shipping and Figures" 1776, is shown on a screen during Sotheby's Important Old Masters Paintings sale in New York, January 27, 2011. The painting sold for $6,200,000. REUTERS/Mike Segar (UNITED STATES - Tags: SOCIETY ENTERTAINMENT)

Auctioneer Henry Wyndham (at podium) takes bids on Claude-Joseph Vernet's "A Grand View Of The Sea Shore Enriched With Buildings, Shipping and Figures" 1776, during Sotheby's Important Old Masters Paintings sale in New York, January 27, 2011. The painting sold for $6,200,000. REUTERS/Mike Segar (UNITED STATES - Tags: SOCIETY ENTERTAINMENT)

The original Aston Martin DB5, driven by actor Sean Connery in the James Bond films "Goldfinger" and "Thunderball", is on display at the venue of Sotheby's Autumn Sales in Hong Kong October 4, 2010. The car will be auctioned on October 27 in London where it is expected to fetch £3,000,000 ($4,737,533). REUTERS/Bobby Yip (CHINA - Tags: BUSINESS SOCIETY TRANSPORT ENTERTAINMENT)

Visitors to the Sotheby's Autumn Sales rest in front of the original Aston Martin DB5, driven by actor Sean Connery in the James Bond films "Goldfinger" and "Thunderball", on display in Hong Kong October 4, 2010. The car will be auctioned on October 27 in London where it is expected to fetch £3,000,000 ($4,737, 534). REUTERS/Bobby Yip (CHINA - Tags: TRANSPORT BUSINESS SOCIETY ENTERTAINMENT)

Julian Gascoigne, Sotheby's specialist on British painting, poses for photographs next to the painting "Modern Rome - Campo Vaccino" by British artist J.M.W. Turner, in central London July 2, 2010. The artwork will be offered in Sotheby's Old Master and Early British Paintings Evening Sale next week and is hoped to fetch between 12 and 18 million pounds ($18-27 million). REUTERS/Paul Hackett (BRITAIN - Tags: BUSINESS SOCIETY)

A lighting technician with Sotheby's Rupert Barth von Wehrenalp (L) holds a flash as Sotheby's staff member Helen Collier poses for photographs next to the painting "Modern Rome - Campo Vaccino" by British artist J.M.W. Turner, in central London July 2, 2010. The artwork will be offered in Sotheby's Old Master and Early British Paintings Evening Sale next week and is hoped to fetch between 12 and 18 million pounds ($18-27 million). REUTERS/Paul Hackett (BRITAIN - Tags: BUSINESS SOCIETY)

A Sotheby's employee wears three gemstones, formerly owned by late fashion model Lucia Moreira Salles and mounted by Paris designer JAR, in New York, December 4, 2009. The jewels are (from L-R) an emerald weighing about 27 carats with an estimated value $400,000-$600,000, a diamond weighing 16.04 carats, F colour, worth an estimated $350,000 to $450,000 and a ruby weighing 16.30 carats expected to sell for between $150,000 and $200,000. The gemstones will be auctioned during Sotheby's New York sale of Magnificent Jewels on December 9. REUTERS/Finbarr O'Reilly (UNITED STATES SOCIETY FASHION)