PIAGET Secret neck watch in yellow gold (750) concealed in a 20-dollar gold coin from 1899. Lid opening by pressing a button concealed in the edge. Round case in yellow gold (750) tilting. Dial with gold bottom, signed, black-painted stick indexes for the hours. Hand-wound mechanical movement. Clip-on back. Gross weight: 34.7 g. - Diameter: 33 mm. Small scratches for use. 00/ Piaget launched the secret coin watch in 1957, whose case was made from a 20-dollar gold coin, partly hollowed out to enclose a thin gold case.