A magical diamond

Understanding Jewellery was first published in 1989 and still enjoys a constant wide international readership having been reprinted 11 times and appeared in several translations including Italian, Hungarian, Japanese and Russian.

Earlier this year a long-awaited Chinese edition has come out to cater for the rapidly expanding interest in antique and period jewellery in mainland China.

The printed version of the book however, does not contain our favourite stone which came up for auction well after the last additions to text and images had been made, although it features in an article published on our website which can be accessed here

There is no question that in our careers at Sotheby’s the most memorable and romantic diamond we have handled, although it was by no means the largest, was the Beau Sancy. This 34.98 carat modified pear double rose cut diamond had been passed down and treasured through the royal families of France, England and Prussia including the House of Orange, and was witness to over four hundred years of history.

We found it to be a truly magical gem when we held it in our hands.

This side shot of the stone shows the unique 'double rose' cut developed for the Beau Sancy

The known history of the gem stretches back to King Henry IV of France, Le Vert Galant, who sent out a quest for the most beautiful and important diamond then available to embellish the crown of his wife Marie de Medici which she was to wear at her coronation in 1610.

Pieter Paul Rubens, Coronation of Marie de Medici, circa 1622-25, Louvre Museum | Marie de Medici is portrayed with the crown set with the Beau Sancy at the front

It should be remembered that the Golconda region of India was effectively the only source of diamonds at this date, and so the stone was infinitely rarer than it would be today.

The diamond is named after its first documented owner, Nicholas Harlay, Seigneur de Sancy. Harlay was a diplomat, financier and ardent monarchist, who is also remembered as the owner of another historic diamond, the 55.23 carat shield-shaped Sancy, which had been purchased from him by King James I of England some years earlier.

Nicholas Harlay, Seigneur de Sancy (1546-1629)

Sadly, the coronation was not to bring to Henry IV any lasting celebrations as he was assassinated by François Ravaillac in a Paris street the following day.

Ravaillac himself came to a particularly cruel end some days later when he was executed by being torn apart by horses.