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Zenith Chronometer, Cal. 40T, Ref. 1021

CHF 1,400


Well-preserved high end, manual-winding, solid 18K gold Zenith chronometer wristwatch, Ref. G 10.21, fitted with Zenith 40T calibre movement  SN: 5658273, made early 1960s. Watch size is 33mm.

Case: Two-body, solid 18 K gold waterproof case, with screwed-in back and golden crown. Movement: Zenith Manufacture Caliber 40 T (18’000 bph, 12 lines, 17 jewels, with an annular balance wheel, mobile balance-spring stud-holder, double arrow index, flat adjustment, shock absorbers, non-deformable pallet-cock with solid buffers, and unbreakable spring). Dial: Silvered dial bearing the mention “Chronomètre”, with golden hands and index appliques and a subdial for the small second (at 6 o’ clock). Dial, movement and case signed. Diam. 33 mm.

With its small second, its 18’000 bph and its 17 jewels, the 40 T caliber constitutes a revised version – mainly produced between 1958 and 1963 – of the already highly precise Zenith caliber 40, enhanced in the case of the “T” version with a lighter annular (screwless) balance wheel, a mobile balance-spring stud-holder which would facilitate the putting into beat of the balance-cock (without having and above all a special bushing for the center arbor, diminishing the risk of premature wear. Also worth noticing in the case of this caliber are its shock absorbers, to be found not only on the balance staff but also on the escapement pinion, thus reducing friction as well as impacts on the regulating device. To top it off, 40 T caliber (as well as the 40 caliber and its contemporaries, the 120, 133 and 71 calibers) was fitted with a double arrow index regulator, developed and patented by Charles Fleck (Zenith’s Precision Timer in chief from 1925 to 1956) and making it easier to rotate the regulator in both directions when adjusting it. remove it), non-deformable pallet-cock with solid buffers, This watch’s caliber’s overall precision was evidenced in this case by the “Chronomètre” mention bore by its dial.

Watch is in overall great condition, running and ready to wear!


Brand Zenith
Model Chronometer
Reference G 10.21
Year early 1960s
Movement Hand-winding
Calibre Zebith 40T
Case material 18K Gold
Case size  33 mm
Bracelet new old stock non-signed leather strap
Features chronometer
Box/Papers no box, no papers


In fully working order. Very good condition, minor surface scratches and scuffs through the age. Unsigned leather bracelet with gold plated steel buckle. No box, no papers.

Watches are sold as-is, and there is no guarantee of to be waterproof or movement accuracy, due to the nature of vintage watches. Please view all the pictures carefully as they form an integral part of the description. Any defects not mentioned but visible in the pictures will be considered as described.


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