Woodcutters in the Black Forest region of Germany invented cuckoo clocks sometime during the 17th century. They derived an extra source of income during winter months by carving pendulum-regulated clocks with a cuckoo emerging every quarter of an hour. The mechanism to produce a cuckoo call was invented a century later. German, and specifically Black Forest, cuckoo clock manufacture became an established business in the 19th century. All the clock parts, the case, decoration and moveable mechanisms, were made of wood. The traditional clock design and its mechanism has remained the same though many manufacturers produce clocks with electronic mechanisms and some synthetic parts.
Examine the back of the clock case. Well known manufacturers such as Hubert Herr, Anton Schneider and Rombach & Haas stamp the back of the clock with a serial number enabling its immediate identification and dating. The makers of the moving parts, such as Hermle and Regula, also stamp a dating code on the back of the clock. Not all manufacturers sign their name on their clocks.
Inquire if the clock has a certificate of authenticity from the Black Forest Clock Association (VDS.) This certificate is provided only for authentic Black Forest clocks that are made entirely of wood.
Remove the back case of the clock and examine the moveable parts. These may have a name or code that enables dating. Consult a reference manual if a serial number is present. Examine the material of the moveable parts. Metal began to replace wood from the early 20th century in cheap, mass-produced cuckoo clocks. The greater the proportion of metal in the moveable parts, the later it was made. Plastic or other synthetic material used for the cuckoo or decorations was introduced after the 1950s. Quartz mechanisms were introduced from the 1970s.
Examine the style of the clock case. The chalet-style, in reality an observation station for railway workers, was adopted by clockmakers from the 1850s and has remained popular. The pine cone design for the pendulum weights was introduced in the 1860s.
Examine the Roman numerals on the clock face. The number four is always IIII and not the usual IV. A number four in the standard Roman style would indicate a modern fake.
Beware of painted cuckoo clocks. Usually, the wood of the exterior case is unpainted. Prior to large-scale manufacture in the 19th century, the earliest cuckoo clocks were painted or enamelled but these items are extremely rare.