The Regent

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

The main facets of both the crown and the pavilion of the magnificent Regent Diamond (now in the Galerie d’Apollon, Musée du Louvre, Paris) are similar in width and shape to those of the Wittelsbach. However, the Regent has fourfold symmetry which is reflected in its culet facets as well as in the split star facets. Both types of facet appear to have been applied in pairs. The Regent, fashioned in London between 1704 and 1706 by a master cutter named Harris, eventually became one of the French Crown Jewels. Because of its excellent proportions and exceptional symmetry, it was regarded for centuries as unrivalled in every respect. Incredible as it may seem, by the application of a deliberately wavy girdle the ingenious cutter produced almost identical angles of inclination of the main facets all round the gem. This obviously resulted in uniform brilliance—virtually unheard of in cushion-shaped diamonds.