Art Deco Onyx and Diamond Pocket Watch by Cartier

• Onyx - Onyx is a form of agate, used from antiquity and popular again in the 1920s and 30s. European onyx is generally green, but can be many other colours, and can contain bands of black and/or white.
  
  This multicoloured stone is widely used for table tops, lamp bases and in jewellery. Some types of onyx are also used for cameos of which the upper white layer is cut away to reveal the colour beneath.
• Lever Escapement - A lever escapement is a type of escapement mechanism used in mechanical clocks and watches to regulate the timekeeping of the movement. It was invented by British clockmaker Thomas Mudge in the 18th century and is now widely used in modern mechanical timepieces.
  
  The lever escapement consists of three main parts: the escape wheel, the pallet fork, and the lever. The escape wheel is a wheel with teeth that is driven by the clock or watch's main spring or weight. The pallet fork is a two-pronged component that is positioned so that it can engage with the teeth of the escape wheel, and the lever is a small, L-shaped component that is attached to the pallet fork.
  
  When the escape wheel turns, one of its teeth pushes against one of the pallet fork's prongs, causing the fork to pivot. As the pallet fork pivots, it releases the tooth and engages with the next tooth on the opposite side of the escape wheel. At the same time, the lever, which is connected to the pallet fork, rocks back and forth, allowing the escape wheel to turn at a regulated rate.
  
  The lever escapement is prized for its accuracy and reliability and is commonly used in high-end mechanical watches. It allows for precise timekeeping by ensuring that the movement of the watch or clock is regulated and consistent, and its compact size makes it an ideal choice for use in small, portable timepieces.
• Chapter Ring - A separate metal plate on the face of a clock, on which the numerals for the hours and sometimes parts of the hours, are displayed, usually wheel shaped and sitting on top of the dial plate. The chapter ring is often a feature of the clock and can be silvered or enamelled to stand as a contrast to its background. The hours are usually shown in Roman numerals, although in the late 19th and earlt 20th century, Arabic numerals became fashionable.
• Art Deco Period - The Art Deco period was a cultural movement that emerged in the 1920s and 1930s, and was characterized by its emphasis on modernism, luxury, and elegance. The name "Art Deco" comes from the Exposition Internationale des Arts Décoratifs et Industriels Modernes, a large exhibition held in Paris in 1925 that showcased the latest trends in decorative arts.
  
  Art Deco was a reaction against the ornate and elaborate styles of the previous era, and reflected a new modern sensibility. It was characterized by streamlined, geometric shapes, bright colours, and the use of new materials such as chrome, glass, and Bakelite. Art Deco designers sought to create a sense of luxury and sophistication, often incorporating expensive materials such as ivory, marble, and rare woods.
  
  Art Deco had a significant impact on a wide range of artistic fields, including architecture, fashion, graphic design, and interior design. Some of the most iconic examples of Art Deco architecture include the Empire State Building in New York City, the Hoover Building in London, and the Palais de Chaillot in Paris.
  
  The Art Deco period came to an end in the 1940s, as World War II and changing cultural trends led to a shift in artistic styles. However, Art Deco remains an important influence on design and art, and continues to be celebrated for its modernist sensibility and glamorous aesthetic.
• Circa - A Latin term meaning 'about', often used in the antique trade to give an approximate date for the piece, usually considered to be five years on either side of the circa year. Thus, circa 1900 means the piece was made about 1900, probably between 1895 and 1905. The expression is sometimes abbreviated to c.1900.

This item has been included into following indexes:

• Breguet (brand) (Switzerland) - pocket watches and wrist watches 81
• Cartier (France), watches - pocket watches 7
• pocket watches, case type - open face, gold / gold-plated case 1,339
• watches - pendant 83