Art Deco Onyx, Enamel and Diamond Pendant-Watch, Charlton & Co., circa 1920

The oval watch face with black Arabic numerals and blued steel hands set within a pendant of pyramidal form decorated with red and black enamel and single-cut diamonds, suspended from a chain of oblong-shaped onyx and red enamel links, surmounted by a circle brooch of onyx, enamel and diamonds, mounted in platinum, dial signed Charlton & Co., movement signed Leschot W. Co., Geneva. 

This watch is illustrated in American Jewelry: Glamour and Tradition, by Penny Proddow and Debra Healy, p. 88, no. 54. 

Like many of his contemporaries, John W. Charlton previously worked for other jewelry firms before opening his own company in 1909. Subsequently, with the addition of a partner, the firm was moved to Fifth Avenue across from St. Patrick's Cathedral and became known as Charlton & Co.  After Charlton's retirement in 1919, his partners continued to run the business and by the late 1920s had opened branches in Palm Beach and Paris.