Magnificent American full diamond brooch watch Circa 1890

Pink gold, platinum and diamond pendant watch 
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A magnificent American 18K pink gold, platinum and diamond set keyless pendant watch, circa 1890. With detachable 18k gold, platinum and diamond crescent form broach. Inner gold and outer platinum case, entirely set with diamonds to the reverse, band and bezel, plain gold hinged cuvette. White enamel dial with radial Roman numerals, outer minute track, gold black painted index and spade hands. Rhodium-plated movement, 18 jewels, captive barrel, Geneva striping decoration, straight-line lever escapement, blued steel flat balance spring, index regulator. Case, dial and movement signed, movement and case also numbered.
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Diameter: 24 mm
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Signed: Tiffany & Co.  New York