There are few clocks in the world which can be expected to sell for pounds 1m at auction. This is one of them - and Christie's is to auction it later this month.
The extraordinary piece, wrought in silver by Carl Faberge, was given to Alexander III of Russia in 1891 to commemorate his 25th wedding anniversary to the Empress Maria Feodorovna, and the 10th anniversary of their coronation.
The clock was the gift of 32 members of the imperial family and is Faberge's most important silver commission - and one of the largest of his works of art - which remains in existence.
Standing 27in high, the clock is shaped in the form of a baroque monument. Its base features a Romanov griffin holding the imperial Russian arms in his right talons and the royal arms of Denmark - the home country of the empress - in its left.
Around the diamond studded clock face swarm 25 figures, one for each year of the marriage, and the piece is surmounted by a triple-crowned Russian imperial double-headed eagle holding a laurel wreath.
Faberge is known to have employed several outsiders to create the work. A court architect called Benois did the design, and the sculptor Aubert made a wax model.
The total cost was 18,585 roubles - an immense fortune at the time.
But it should sell for another on 18 April, when it will be the star lot in a sale of Russian works of art, paintings and Faberge at Christie's New York.