Abstract: A self-compensating spring for a balance-spring for a balance-spring/balance assembly of a mechanical oscillator of a horological movement or of any other precision instrument, made of a paramagnetic Nb--Zr alloy containing between 5% and 25% by weight of Zr, obtained by cold rolling or cold drawing, and having a Young's modulus whose temperature coefficient (TCY) is adjustable by precipitation of Zr-rich phases in the Nb--Zr solid-solution. It contains at least 500 ppm by weight of an interstitial doping agent at least partly formed of oxygen.

Abstract: A wristwatch case includes a caseband (12) which receives a movement (2) surmounted by a dial (3). A crystal (5) and a back cover (6) are secured to the caseband as well as first (7) and second (8) bracelet strands. The back cover entirely covers over the underside of the caseband and includes first (9) and second (10) integrally formed wings. Such wings cover over entirely the outer sides (11) exhibited by the caseband and which are found situated between the bracelet strands. The back cover is preferably made of ceramic material.

Abstract: The clasp (1) is telescopically extensible. It includes a first tubular element (2) capped on its upper and lateral faces by a plurality of links (5) resembling those employed for the rest of the bracelet. Into the first element there may be introduced a second tubular element (8) which in turn is adapted to accommodate a third element (10) in the form of a plate to which is attached a blocking system in order to maintain the clasp in its retracted position. The clasp is for a bracelet and shows no greater thickness relative to the links forming said bracelet.

Abstract: The method of manufacture of this watch case consists in employing a material including at least 95% copper in its composition, the remainder being made up of elements adapted to increase the mechanical strength of the copper while avoiding the toxic elements beryllium and cadmium. Thanks to this material the watch case may be stamped out in a single operation, hardened, then covered with a protective layer deposited galvanically or by a PVD process.