Swiss lapel watch with diamond and ruby set brooch Circa 1910

Platinum sapphire and diamond set watch
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A very fine and unusual, platinum, sapphire and diamond set, keyless, lapel watch with articulated integral diamond and ruby set brooch. Accompanied by a box and made for Black, Starr & Frost by Ed. Koehn, Geneva, Switzerland Circa 1910. Two body, solid and polished case with hinged case back, bezel pave set with rows of diamonds and rubies and the corners set with four pear-shaped diamonds.
Matte silver dial with painted Arabic numerals, outer minute track and blued steel spade hands. Tonneau shaped and rhodium-plated movement with 16 jewels, straight-line lever escapement, cut bimetallic compensation balance adjusted to 7 positions and blued steel flat balance spring.
Case signed Black, Starr & Frost, movement signed Ed. Koehn, Geneva, Switzerland.
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Dimensions: 14 x 25 mm
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Thickness: 6 mm
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Signed: Black, Starr & Frost