Designed circa 1925-1930 by Cartier Paris, this unusual skeleton watch is composed of rock crystal, platinum, diamonds, and a Jaeger movement, and is offered with a later platinum and seed pearl chain. The case with a triangular platinum bow is formed of a polished rock crystal disk with faceted borders and edged by platinum, the skeletonized rose-cut diamond Roman numeral chapter ring surrounding the silvered engine-turned dial and minute ring with abstract numeral indicators and blued steel "Breguet" hands. Its Jaeger European Watch & Clock 19-jewel lever escapement movement with Côtes de Genève decoration has 8 adjustments. The several variations of this elegant Cartier rock crystal watch of slim dimensions proved enduringly popular throughout the 1910s-1920s, with this uncommon skeletonized version adding a definite touch of mystery and intrigue to the design.