English triple cased watch for Ottoman market Circa 1792

Silver open faced pocket watch by George Prior
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A very heavy English verge pocket watch with three cases and hallmarks for the Ottoman market, circa 1792.
Three cases: 1st case with tortoiseshell and pin decoration; 2nd case silver with hallmarks London 1792; 3rd case also silver with hallmarks. Fire gilt verge movement, signed “Geo Prior London“, splendid verge bridge with monogram GP for George Prior, very decorative pillars. Signed enamel dial with Ottoman numerals, original steel hands and probably original key.
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Diameter: 73 mm
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Weight: 201 g
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Signed: George Prior London