Rolex. A rare 18K gold quartz calendar bracelet watch
Model: 'Texan' Beta 21
Reference: 5100, No.416
Date: Circa 1970
Movement: 13-jewel Beta 21 quartz, No.7132
Dial: Champagne, applied gilt baton hour markers, black 1/5th second divisions, magnified date aperture at 3, gilt baton hands with luminous inserts, centre seconds
Case: Brushed tonneau form, back secured by sliding bars, fluted bezel
Strap/Bracelet: Fitted brushed link
Buckle/Clasp: Signed 18K gold folding clasp
Signed: Case, dial & movement
Size: 40mm
Footnotes:
The Beta-21 was developed by the Centre Electronique Horloger formed by Omega together with approximately 20 other Swiss watch companies including Piaget, Rolex and Patek Philippe in 1969. The Beta-21 movement was accurate to 5 seconds per month, which was superior to any other automatic and manual wind watch at the time.

In 1970 Rolex released the reference 5100, housing the Beta-21 in a 40mm solid gold case. Whilst Rolex never confirmed production numbers it is rumoured that only 1000 pieces were made, with 900 in yellow gold and 100 in white gold.