The invention relates to a barrel spring (2) including: an inner end (5) and an outer end; a first portion (50) having a first height (H); a second portion (52) having a second height (h) that is smaller than the first height (H) and being located near the inner end (5); and, at the second portion, e.g. at the inner end, a first attachment element (51) suitable for being attached to the barrel shaft, wherein the second portion is to be inserted into a circumferentially extending groove provided on the barrel shaft.

The invention relates to a barrel spring (2) including: an inner end (5) and an outer end; a first portion (50) having a first height (H); a second portion (52) having a second height (h) that is smaller than the first height (H) and being located near the inner end (5); and, at the second portion, e.g. at the inner end, a first attachment element (51) suitable for being attached to the barrel shaft, wherein the second portion is to be inserted into a circumferentially extending groove provided on the barrel shaft.

The method of manufacturing a timepiece shaft (1) includes grinding a ceramic piece, especially to form a balance shaft (1), having a functional portion (2a; 2b) including at least one part (221a; 221b) of a pivot-shank (22a; 22b) and/or at least one part (211a; 211b) of a pivot (21a; 21b), the first functional portion being made of ceramic and a first outer diameter (D1) of the first functional portion being less than 0.5 mm, or less than 0.4 mm, or less than 0.2 mm, or less than 0.1 mm.

The method of manufacturing a timepiece shaft (1) includes grinding a ceramic piece, especially to form a balance shaft (1), having a functional portion (2a; 2b) including at least one part (221a; 221b) of a pivot-shank (22a; 22b) and/or at least one part (211a; 211b) of a pivot (21a; 21b), the first functional portion being made of ceramic and a first outer diameter (D1) of the first functional portion being less than 0.5 mm, or less than 0.4 mm, or less than 0.2 mm, or less than 0.1 mm.

A timepiece mainspring is accommodated inside a barrel, an inner end thereof is fixed to a barrel arbor included in the barrel, and an outer end thereof engages with an inner wall of the barrel. The timepiece mainspring includes a helical portion wound in a Bernoulli curve shape from the inner end in a free state having no applied load.

A timepiece mainspring is accommodated inside a barrel, an inner end thereof is fixed to a barrel arbor included in the barrel, and an outer end thereof engages with an inner wall of the barrel. The timepiece mainspring includes a helical portion wound in a Bernoulli curve shape from the inner end in a free state having no applied load.

Timepiece wheel set with a unidirectional wheel rotating in only one direction in cooperation with a ratchet wheel, which is movable inside a ratchet wheel chamber, comprising a click that rotates integrally with this wheel, which forms a one-piece component comprising at least one spring-arm, at the end of which, on a first side, a beak cooperates directly with the toothing of a ratchet wheel in an operating position in which this spring-arm is free, and on a second side, a first hook can cooperate with a second hook of complementary shape, comprised in this one-piece click, in a rest position in which this spring-arm is in an extended position, the elasticity thereof allowing this first hook to be hooked or unhooked with respect to this second hook by the action of an operator, by maximum elongation of this spring-arm and/or by the tilting of this end.

Timepiece wheel set with a unidirectional wheel rotating in only one direction in cooperation with a ratchet wheel, which is movable inside a ratchet wheel chamber, comprising a click that rotates integrally with this wheel, which forms a one-piece component comprising at least one spring-arm, at the end of which, on a first side, a beak cooperates directly with the toothing of a ratchet wheel in an operating position in which this spring-arm is free, and on a second side, a first hook can cooperate with a second hook of complementary shape, comprised in this one-piece click, in a rest position in which this spring-arm is in an extended position, the elasticity thereof allowing this first hook to be hooked or unhooked with respect to this second hook by the action of an operator, by maximum elongation of this spring-arm and/or by the tilting of this end.

For example, an escape gear portion as a watch component includes a substrate containing silicon as a main component, and a light reflecting layer including a first silicon oxide layer, a silicon layer, and a second silicon oxide layer that are stacked, in this order, at the substrate, wherein, when the light reflecting layer is viewed in plan view, the light reflecting layer includes a first region and a second region, and a thickness of the silicon layer in the first region is different from a thickness of the silicon layer in the second region.

For example, an escape gear portion as a watch component includes a substrate containing silicon as a main component, and a light reflecting layer including a first silicon oxide layer, a silicon layer, and a second silicon oxide layer that are stacked, in this order, at the substrate, wherein, when the light reflecting layer is viewed in plan view, the light reflecting layer includes a first region and a second region, and a thickness of the silicon layer in the first region is different from a thickness of the silicon layer in the second region.