What exactly is an 'Art Deco' watch?

This may interest you:

https://www.catawiki.com/en/stories/1611-the-story-behind-art-deco-watches-1920-1950

Sector dial watches maybe ?

Art Deco is defined by geometric patterns, often repeated and stylised, occasionally influenced by Egyptology. Quite a lot of those stating art deco are just of the period or with Roman numerals, neither of which makes them so. Stylised Arabic numerals are more of a nod. Colour wise it's either bold contrast (black and white, silver, or gold, or combination of 3 of them) or it very colourful.

Here's our house number, repeated geometric design and stylised numeral.

According to Wiki ....Art Deco combined the styles of early 20th century Modernist avant-garde, with the fine craftsmanship and rich materials of French historic design, but also sometimes with motifs taken from non-Western cultures.

Alexander Shorokoff avant-garde collection is really cool except they put the full name usually on the dial

https://www.alexander-shorokhoff-shop.de/en/produkt-kategorie/avantgarde-en/?_ga=2.6322802.1973663111.1709472750-59087711.1709472750

Art Deco is an early 20th Century art style that can be viewed as a progression of the Arts & Crafts and Art Nouveau movements. Lines and patterns are important, stylized fonts and shapes, Orientalism and Exoticism, it's less organic/nature oriented than Arts & Crafts but with more flourish and flamboyance than the later Mid-Century Modern. Most people just think "1930's" but that was actually the end of Art Deco, late-WW1 through the 20's are what I think of as peak Art Deco. Anyway, watches in the style will be bold, daring, colorful or with strong contrast, line work will feature prominently, and while there may be subdued but there is no subtle with Art Deco!

https://youtu.be/ZHF7vnbZD8Q?si=PXN6eN0LXPEajKV5

Art Deco explained in 9 Minutes

JLC clasic REVERSO is the perfect example ...

The Cartier Tank is one of the foundational designs of the Art Deco movement. Most of the rectangular watches that followed it - and were so popular in the 20s and 30s heyday of the style - are exemplars of the style.

By the time of the Exposition Internationale des Arts Décoratifs et Industriels Modernes, which gave the movement it's name, Cartier's influence had permeated the design world. Cartier itself exhibited over 50 items at the exposition.

Most of the watches that tout their Art Deco styling today are putting deco elements like fonts, sector dials and ziggurat steps onto what is, at heart, a Bauhaus design; the Calatrava case.

1930s Elgin

Vacheron Constantin Historiques 1942 ... A banger!