A wristlet clasp (100), of the folding buckle type, including first and second blades (1, 2) hinged relative to each other, the first blade (1) further including locking means for holding the first and second blades (1, 2) in their closed position at its second end, and the second blade (2) carrying a member for fastening a first wristlet strand at its second end. The first and second blades are hinged together by movable blades (3, 4) by a first of their respective ends, the hinged blades being connected to the first and second blades via a first hinge (A1) and a second hinge (A2), the hinge (A1, A2) being angularly delimited by stops respectively formed on the first end of the first and second blades and on the second end of the movable blades so as to define two predefined wearing positions depending on the size of the wrist.