Abstract: 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.