ST PETERSBURG, RUSSIA - OCTOBER 13, 2021: The Ludo secret watch by Van Cleef & Arpels is on display at an exhibition of watches nominated for the 2021 Grand Prix d'Horlogerie de Geneve (Geneva Watchmaking Grand Prix, GPHG). Eighty-four watches by the world's leading brands are on display at the exhibition. Alexander Demianchuk/TASS (Photo by Alexander Demianchuk\TASS via Getty Images)
