A movable decorative element, intended to be freely rotated and translated between two walls (5, 6) whose inner faces are parallel to each other, at least one of which is transparent, includes a precious or semi-precious stone (2) mounted in a socket (1). The socket (1) includes a closed bottom (4) whose outer face is bulged to promote the rotation of the decorative element when this bulged outer face (7) is applied against the inner face of one of said walls, and an open outer (7) opposite to the bottom (4) which is flush with or which protrudes relative to the stone (2) to form a bearing surface against the other of said walls (5, 6) when the decorative element is disposed between the two walls. The precious or semi-precious stone (2) is held in its socket (1) by a plurality of arms (3) which extend above a body (8) of the socket (1) and which crimp the stone (2), these arms (3) leaving, therebetween and above the body (8) of the socket (1), lateral openings (9) letting appear the flanks of the stone (2) between the arms (3), and said bearing surface is constituted by the free ends of said arms (3) in the form of separate contact areas spaced from each other around the periphery of the open outer face (7) of the socket (1).