Balance-spring stud holder device

A balance-spring stud holder intended to be mounted on a balance bridge of a timepiece mechanical movement and comprising a part for attaching a balance-spring stud and a clamping part that is designed to be able to clamp a lateral wall of a projecting part of the balance bridge or of a piece mounted on this balance bridge;

• wherein the clamping part defines three contact zones intended, once the balance-spring stud holder is mounted on the balance bridge, to press against the lateral wall of the projecting part or piece, a first contact zone from the three contact zones being connected to a second contact zone from these three contact zones, the second contact zone is adjacent to the first contact zone, by a first part of the clamping part, and the clamping part has, between the first and second contact zones, a first separation zone, and to a third contact zone from the three contact zones, the third contact zone is also adjacent to the first contact zone, by a second part of the clamping part that has, between the first and third contact zones, a second separation zone, the first and second separation zones being provided, once the balance-spring stud holder is mounted on the balance bridge, recessed from the lateral wall of the projecting part or piece;
• and wherein, in a general plane in which the clamping part extends overall, the first part has a first stiffness at a second median point of said second contact zone, relative to a first median point of said first contact zone, the first stiffness is greater than three times a second stiffness that said second part has at a third median point of said third contact zone relative to the first median point of the first contact zone.