ETIENNE TAVERNIER CIRCA 1800 Astronomical double-sided watch key with calendar, French work. CASE: round with straight edge in polished yellow gold, screw and pusher on the caseband, flat and smooth reverse with half-opening for the enamelled moon phases, engraved graduation for the ages of the moon, the end of the key is missing. DIAL: white enamel (two cracks), date painted in gold and days of the week in blue, blued steel hands, signed. MOVEMENT: triggers the mechanism, day, date and moon phases when the key is inserted for winding. DIAM. 24 mm. GROSS WEIGHT: 12.00 g. Condition report on request Condition report on request