Diamond and emerald ring, 1920s. Around the beginning of the 20^th century, developments in stone cutting meant that gemstones and diamonds could be shaped in more diverse ways than ever before. The different arrangements of these new shapes, such as the new rectangular ‘baguette’ cut, gave jewellers a newfound fascination with simple geometric designs constructed from tessellated shapes, which led to the development of the Art Deco style. This ring is a tour de force of design from this era, with unusually-shaped trapezoid and ‘bullet cut’ diamonds forming a central panel, surrounded by a millegrained border of circular-cut diamonds, accented at each end with a pair of carré-cut diamonds. The two perfectly tessellated bands of emeralds across the centre were cut specifically to fit the mount. Emeralds are the most difficult and expensive stones to cut and set in this way, as due to their inherent brittleness they would often break in the process. This ring is a superb example of early 20^th century jewellery design, and would make an unusual and attractive choice for an engagement ring, or a standalone statement ring.