The Estanque

(via Diamond Cuts in Historic Jewelry:1381-1910) Herbert Tillander writes:

During his travels in the Netherlands towards the end of 1559, King Philip II of Spain bought the largest diamond ever seen in Europe. The merchant who sold him the rough stone was (according to Charles de Lecluse, who spells the name in various ways) Juan Carlos Affaitatus. King Philip had the stone fashioned into a single exceptionally fine gem weighing nearly 50 ct, which was given the name of Estanque, meaning ‘impervious’ or ‘adamantine’. He presented the diamond, and the famous Peregrina pearl, to his third wife Elizabeth of Valois as a wedding present. On 13th February 1560 she rode in state into Toledo, wearing both these jewels and another large Table Cut diamond. This second Table can be seen in portraits of the English Queen, Mary Tudor, Philp’s second wife, on whose death in 1558 the diamond returned to the Spanish Crown.

Large Table Cut diamonds were the height of fashion in Spain at that time; they often had drop-shaped pearls suspended from them. The Peregrina and the Estanque were later combined into one jewel known as the Joyel Rico or the Jewel of the Austrias, which suggests that it was created for Philip’s fourth wife, Anne of Austria.

It has only been possible to analyze the cut of the stone through the efforts of Dr Muller, who discovered a most interesting description in Saez Diez’s manual for jewelers, published in 1781. Diez claimed that the area of the gem was equal to the area of a 56ct diamond. He had not actually seen the gem, but it is clear that a trustworthy informant had compared the size of the Estanque with Jeffries’ charts.

A number of portraits of Spanish queens show the Estanque diamond, but in most of them the brushwork is imprecise. However, in the portrait of Margarita of Austria, wife of Philip III of Spain, Bartolomé Gonzales (appointed Pintor del Rei in 1617) has reproduced the gem with exceptional accuracy. He shows the size of the table and the culet, the stepping of the pavilion, and the reflections of the culet in the crown facets. These last indicate that it was a shallow stone.

Drawing of the Estanque diamond: diameter of 22mm, a table size of 78 percent and a crown height of 11 percent. The angles of inclination are 45° both above and below the girdle. The application of a step near the culet was a device widely used in Antwerp throughout the period when Table Cuts remained in fashion. It made it possible to reduce the size of the culet and at the same time to retain the 45° angles of the pavilion. If the step was applied at precisely the right point, it gave increased reflections of light from the pavilion. The broken lines in the diagram indicate the shape of a standard High Table Cut.

Two other painting of the Estanque diamond confirm my analysis of it: a portrait of Queen Anna by Alonso Sanchez Coello and a portrait of Queen Margarita, said to have been painted by Diego Velázquez and his studio.