What would you pay for an object so rare that it is thought to be the only one of its kind in the world?

Well, Dh1 million is the amount you will have to spend if you want to own a museum-quality, 19th century astronomical long-case regulator by Henri Robert.

Ron Palladino, President of Solvang Antique Centre, California, told Emirates Business: "The principle value of this clock is its intrinsic value, as one could not duplicate it today for Dh1m. Beyond that, the value is enhanced by the fact that it is a one-of-a-kind clock of exceptional design and made by one of the most famous and sought-after clockmakers in French history, Henri Robert.

"When you compare a museum-quality clock like this with a equally rare and fine example in the field of art, furniture or Americana you realise how undervalued important clocks can be. The price is a fraction of what you would have to pay for anything of its equal in collector markets," said Palladino.

"This is because there is only one of them in the world and no evidence of anyone in history having made a clock even remotely similar to this one," he said.

A rare astronomical long-case regulator with equation of time and observatory strike, this remarkable precision jeweller's regulator is a resounding tribute to the aesthetic and engineering talents of the extraordinary clockmaker Robert.

Robert lived from 1795 to 1874, and practiced his trade at Rue de Valois from 1832.

The movement runs 14 days on a winding, powered by a hidden weight.

The porcelain and gilt brass dial elegantly indicates minutes, hours and sweep centre seconds on a porcelain chapter ring; power reserve on an arched sector dial; the date and equation of time on an engraved and silvered subsidiary dial.

The massive 32-pound temperature compensating Harrison gridiron pendulum assures precision timekeeping. The rare observatory strike sounds a bell each second upon demand, allowing the astronomer to record the time, while observing the movement of a star or planet. It is not surprising to learn that Henri Robert was a protégé of Abraham Louis Breguet, the most important clock and watchmaker in French history, in addition to Louis Frédérique Perrelet. This breathtaking 94-inch example of his horological genius certainly does credit to his mentors and confirms his well-deserved position among the finest horologists of his era.

Palladino said: "The movement is a one-of-a-kind creation, showing both mechanical time and solar time. This feature is called equation of time, as it gives you the exact number of minutes to add or subtract when setting your clock to a sundial reference.

"In addition, it has a calendar function and a power reserve indicator which shows how many days it has been running. Unlike most clocks, which need to be wound once a week, this one runs for 14 days on a winding.

"The case also is a masterpiece of the French furniture making art. It is constructed in a rare type of Brazilian Rosewood, which is an endangered species today.

"The castings are done in bronze and would have been gilded using mercury to fuse the gold to the bronze ormolu. This process was banned in the mid-1800's because the fumes of the mercury were deadly to the workers performing this process.

"We can only assume that someone of royal, or financially equivalent status, commissioned this clock with no regard to cost. Most astronomical regulators were working tools housed in modest cases. Only someone of extraordinary wealth and taste would command a cabinet as extravagant in materials and artistry as the movement is in its engineering and mechanical execution.

"The result is a masterpiece of mid-19th century horology, equal to many of the best examples in the world's finest museums," said Palladino.