14ct rose gold 'Bubble back' with steel caseback wristwatch. Made 1940's

Information

• Brand: Rolex
• Year: Circa 1940
• Model: Oyster Perpetual
• Reference: 3131
• Calibre: 9 3/4'''
• Movement: Automatic
• Material: 14ct rose gold
• Features/complications: Bubble back 
• Dial: Black dial with outer minute track featuring luminous baton hour indices and Arabic quarters with luminous Oyster hour and minute hands and sweep centre centre seconds 
• Case dimensions: 32mm
• Bracelet/strap: Leather strap
• Accessories: N/A
• SKU: 2236

Essay

Rolex created the auto-rotor movement from the Aegler movement in Hunter watches that featured a “perpetual motion” winding mass. Rolex subsequently patented its first successful perpetually self-winding wristwatch in 1932 and the Bubble Back was introduced in 1933 and featured the first auto-rotor. The reference 3131 is yet another model of a long line of a Oyster Perpetual wristwatches since their inception in 1926