22ct/18ct yellow gold Piaget $20 coin wristwatch. Made 1975

Information

• Brand: Piaget
• Made: 1975
• Model: $20 coin watch
• Reference: 900B
• Calibre: 9P
• Movement: Manual 
• Material: 18ct yellow gold
• Features/complications: Hinged case within a United States of America $20 gold coin
• Dial: Yellow gold dial with outer minute track featuring black printed hour markers  with baton shaped hands
• Case dimensions: 35 mm
• Bracelet/strap: Leather strap
• Accessories: N/A
• SKU: 3104

Essay

The coin watch is a fascinating niche area of horology. Originally the coin watch was dreamt up by brands trying to demonstrate their technical prowess in the ability to fit a movement within the thin confines of a coin. This was usually accomplished buy joining two coins together so there would be sufficient material within which a movement can sit. This was until 1957 at the Basel fair when Piaget unveiled their 9P movement showcased in a coin watch. A single coin was used, divided in half and hollowed out with a sprung cover that revealed the dial at the push of a button.