Although I find myself saying this a lot, the Beau Sancy must surely be one of the most beautiful diamonds in the world, a perfect combination of technical skill, artistic beauty, impeccable provenance and documented history.
A modified pear shape double rose cut diamond, with the facets centred on an eight sided star, it weighs 34.98 carats and was graded by the GIA as K colour (faint brown modifier) and SI1 clarity. It was tested as being of Type II category, the most chemically pure diamond category, which often have exceptional transparency. It almost certainly came from the Golconda region of India, from where most of the world’s most famous diamonds came.
The Beau Sancy diamond takes its name from Lord of Sancy, Nicholas de Harlay, French Ambassador to India, who brought the diamond to France from India. Its larger sibling diamond, the Grand Sancy (55 carats), was sold to James I of England to wear in his hat. This infuriated Marie de Médicis, wife of the French king Henri IV, and richest heiress in all of Europe. She nagged her husband until he bought it for her. King Henri was deeply in debt to her family when he married de Médicis, daughter of the wealthy Italian aristocrats. Her dowry included the debt being written off, and a casket full of diamonds pearls and precious stones, prompting his mistress to nickname her “the fat banker”!
De Médicis was descended from the Medici family through her father, the Grand Duke of Tuscany, and from the Hapsburgs through her mother, the daughter of the Emperor of Austria.
She wore it in her pearl and diamond crown on her coronation day. Tragically, a day after her coronation in May 1610, the king was assassinated, leaving six children under the age of nine. He was killed by François Ravaillac, to stop the French king waging war against Spain. The heir to the throne, Louis XIII, was only nine years of age, so Catherine became Regent.
Her reign came to an end in 1617, when her son had her exiled, fearful that he might be assassinated by de Médicis’ favourite (Concino Concini). She was sent to the Castle of Blois in the Loire Valley. She escaped two years later with a rope ladder, taking the jewel with her.
After two years of wars with her son, her armies were defeated; her son realised that it was better to keep her close to him where he could keep an eye on her, and built a palace for her in Paris, the Palais de Luxembourg. This is where the French Senate sits today.
In 1631, de Médicis was Queen Mother (and now greatly in debt herself). Further quarrels with her son and with Cardinal Richelieu made her position untenable, and she fled to Brussels. The King stopped her pension, and she lived out her life funded by selling or pawning her jewellery.
She sold the diamond to the Dutch Royal family (Prince Frederick Hendrik and his wife, Amalia von Solms), who had become very wealthy through maritime expansion and commercial growth. It is not exactly clear when he agreed to buy it, but we know that he paid 80,000 gilders for it in 1642.
It sealed the wedding of William II of Orange to Mary Stuart, daughter of King Charles I (she was only ten years old at the time). Stuart was to later pawn the diamond to fund her brother’s (Charles II) fight for the Throne of England.
It returned to royal ownership when her son William III of Orange-Nassau married Mary II. They were to jointly rule England until her death in 1694. When he died without heirs, the Beau Sancy was returned to the Dutch family and then, in 1701, to the first Prussian Kaiser, Frederick I, in 1701. It was to stay in that family, as far as we can tell, for three hundred years, until it was sold by Sotheby’s in 2012 for 9.7 million dollars.