Extremely rare American lever chronometer watch Circa 1870

Gold open faced pocket watch by Edward Howard & Co.
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A very fine, extremely rare American gentleman’s pocket watch, lever chronometer, circa 1870 – so called Blue Sapphire, with large blue sapphire jewels – only 500 pieces of the famous Blue Sapphire were created, this watch bears the no. 209.
18 Carat gold, polished, à goutte case with a numbered and signed gold dome. Signed enamel dial with Arabic numerals, auxiliary seconds, and blued spade hands. Signed, frosted, gilt bridge movement, with wolf teeth winding wheels, Patent D’05’10, blue sapphire end stones on balance, lever and escape wheel, blue sapphire jewels, bimetallic chronometer balance with gold and platinum screws and two star shaped regulation weights, and blued helical free sprung balance spring with a terminal inner curve.
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Diameter: 51 mm
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Weight: 103 g
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Signed: Edward Howard & Co., Boston
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Most striking about this pocket watch are the large blue sapphire jewels – which are the reason why some collectors call the watch the “Blue Sapphire”. This is regarded to be the best pocket watch calibre ever produced in the United States.