Extensible clasp for a bracelet

An extensible clasp for a bracelet, in particular for a watch bracelet of an unfolding buckle type, including a first assembly comprising a cap to which is secured a first bracelet strand and a push-piece permitting opening of the clasp and an adjustment of a length of the clasp, said push-piece emerging from an opening formed in a side of the cap, and a second assembly on which the first assembly is adapted to slide in a longitudinal direction of the bracelet, such second assembly comprising first and second blades foldable back on one another and attached together at their first ends by an articulation, the first blade having a hook while its second end has a means for attaching to a second bracelet strand, the second blade being attached by an articulation at its second end to an arrangement which the hook can grasp so as to block the clasp, and on which the push-piece acts in order to open the clasp by allowing the first and second blades to be folded away from one another, said arrangement and said push-piece being respectively provided with indexing means and positioning means which release from and interengage with one another for permitting adjustment in length of the clasp and for retaining in memory such adjustment when said clasp is opened.