English gold precision minute tourbillon watch Circa 1910

Gold watch with minute tourbillon
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An important, heavy precision pocket watch with minute tourbillon. The case is 18k gold, tiered, smooth, case maker punch mark “AB”, glazed movement, turning pendant. with silvered dial, radial Roman numerals, auxiliary seconds, 36h power reserve indication, signed, numbered, blued spade hands. 3/4 plate movement, frosted, gilt, chatoned, engraved barrel: “To H. M. The King of Spain”, blued screws, chain/fusee, Swiss lever escapement, Guillaume gold screw compensation balance with platinum regulation screws, finest mirror-polished tourbillon steel cage, blued balance spring.
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Diameter: 57 mm
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Weight: 170 g
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Signed: Smith & Son London