A golden jug worth over GBP 1 million that the French King Louis XV gave to his mistress is to be sold at auction.

An exceptional goldsmith and silversmith collection that belongs to famous Belgian antique dealer Bernard De Leye will be auctioned at the Lempertz Auction house in the Germany city of Cologne on 15th July.

The art dealer’s personal collection, which he gathered for decades, consists of 220 artworks such as objects of vertu, silverwork, paintings and sculptures, including a silver gilt ewer estimated at EUR 1.2 million (GBP 1 million).

The exquisite object was made by the French silversmith Jean-Baptiste-Francois Cheret in Paris in 1770.

The jug, which is one of the most expensive in the world, was given as a gift by the French King Louis XV to his mistress Marguerite Catherine Hainault (1736-1823), who bore him several illegitimate children, on the occasion of her betrothal to a colonel in the French army, at which time he also proclaimed them the Marquis and Marquise de Montmelas.

Lempertz owner Hendrik Hanstein, 70, said: “I have never seen or been allowed to offer such a treasure.”

When asked for his opinion about the EUR-6 million (GBP-5.17 million) collection, Hanstein said: “This art is for showing off, not for using. Incredible pieces. More valuable than the entire arts and crafts museum in Cologne.”

The collection includes several other highly valuable pieces such as a silver and gilt bronze writing set, estimated at EUR 700,000 to 800,000 (GBP 603,000 to 690,000) and made for imperial minister Jean-Baptiste de Machault d’Arnouville by Francois-Thomas Germain in 1753.

Another significant piece is a monumental silver and lapis lazuli hourglass which has been valued at EUR 400,000 to 450,000 (GBP 345,000 to 388,000) which was created in the Italian city of Rome in 1589.

A Lempertz spokesperson told Newsflash that Pope Sixtus V (1521-1590) presented this exceptional sandglass to Ferdinand I de Medici (1549-1609) who was the Grand Duke of Tuscany on the occasion of his marriage to Christine von Lothringen.

Another one includes a small equestrian statue of Emperor Ferdinand III (1478-1638) made of silver and partially gilded with a removable head part.

Hanstein explained: “From this one, we can conclude that small equestrian statues served as symbols of the Habsburg reign and not for individual fame.”

Holding a Roman silver bowl from the second or third century AD, estimated at EUR 30,000 (GBP 26,000), the 70-year-old expert explained that such gifts were based on the rank and status of the recipient and were often associated with additional monetary gifts.

He said: “The recipient displayed the object as a status symbol.”

The preview for all artworks will take place from 21st to 26th June in the Belgian capital Brussels, and from 5th to 15th July in the German city of Cologne.

The auction is scheduled for 15th July in Cologne.