AUDEMARS PIGUET REF. 25820 ROYAL OAK PERPETUAL CALENDAR MOTHER OF PEARL DIAL, PLATINUM Audemars Piguet, Genève, Royal Oak, Quantième Perpétuel Automatic," No. 010, case No. D 7781, Ref. 25686. Sold on November 13, 1992. Very fine and rare, octagonal, astronomic, self-winding, water-resistant, platinum wristwatch with perpetual calendar, phases and age of the moon and a platinum Royal Oak bracelet with 18k white gold deployant clasp. Accompanied by the original winding fitted box, original warranty and instruction manual. Three-body, polished and brushed, octagonal bezel with 8 hexagonal recessed white gold nuts screwed to eight screws on the transparent case back, hexagonal winding crown, sapphire crystals. Mother-of-pearl with applied luminous white gold indexes, subsidiary dials for the days of the month, of the week, the months and the age of the moon, aperture for the moon phases. Luminous white gold baton hands. Cal. 2120/4, rhodium-plated, 38 jewels, straight-line lever escapement, monometallic balance adjusted to heat, cold, isochronism and 5 positions, shock absorber, self-compensating fl at balance spring, engraved 18K yellow gold rotor segment. Dial, case and movement signed. Diam. 39 mm. Thickness 10 mm. Approx. overall length 170 mm.