Curse of the Sh21.5billion watch strikes again as billionaire owner dies two days before it's sold

London, England: Sheikh Saud Bin Mohammed Al-Thani, died suddenly, aged 48, continuing a catalogue of misfortune associated with the watch.

It's known as the most beautiful watch in the world - but is it tarnished by a deadly 'curse'?

Sheikh Saud bin Mohammed Al-Thani, the owner of the world's most expensive watch worth £15million, has died suddenly at his London home last week.

The 48-year-old billionaire, who was known as one of the biggest art collectors in the world, wanted to sell the watch and had it prepared to be put up for auction in two days time.

But he passed away after suffering complications from a heart condition.

The 1933 Patek Phillipe timepiece has brought ill-luck and tragedy to its owners.

The curse stretches back to to its first owner Henry Graves, who approached legendary watchmaker Patek Phillipe to make him the world's most complicated watch in 1925.

Seven months after Graves took possession, his best friend died and a short time later his son George was killed in a car crash.

The 48-year-old Qatari royal bought the watch 15 years ago for $11M.

It was sold in Geneva to an undisclosed buyer for a record 23M Swiss francs, but it has emerged that the sheik had passed away two days earlier.

It took Swiss horologists three years to research and a further five to make, completing it in 1933.

The watch has a gold openface minute repeating chronograph clockwatch with Westminster chimes.

It also features a perpetual calendar, moon phases, sidereal time, power reserve, and indications for time of sunset and sunrise and the night sky of New York City.

In total, there are 24 horological complications and 'The Graves' held the title of the world's most complicated watch for 56 years.

It was last auctioned off in 1999 for $11 million (£9.6m) and has a lower end reserve price of $15.6m (£9.8m) in the current sale.

The buyer on that occasion is thought to have been Sheikh Saud bin Mohammed Al-Thani, the former minister of culture and heritage in Qatar.

He later gave it to Sotheby's to help cover an unpaid debt.