Jewellery watch, brooch. SIGMA VALMON Geneva. Early 20th century Model representing a cuckoo clock. Gold, turquoises, old-cut diamonds, rubies, a sapphire and enamels. Original leather and silk case. Weight: 19.2 g. Measurements: 6.3 cm (length); 1 cm (dial) The cuckoo clock is a type of clock generally fitted with a pendulum and a gong, characterised by an opening through which, every half hour, a bird-shaped automaton emerges, generally resembling a cuckoo, and which therefore emits a song, the sounds of which resemble the onomatopoeia "cuckoo". This piece belongs to the personal collection of Don Juan José Ontalva (Chinchón, 1930- Madrid, 2019), a famous watchmaker from Madrid, descendant of several family generations dedicated to the world of watches. During his career he achieved a high degree of precision and skill, becoming the master of other watchmakers. He is currently recognised for numerous works, including the commissioning and restoration of the Billeter astronomical clock, located in the Congress of Deputies.