The Cartier Santos Octagon reference 0907 is a vintage ladies' automatic watch produced primarily during the 1980s and early 1990s.  It is distinguished by its unique octagonal bezel, a design element reminiscent of the Audemars Piguet Royal Oak, set within a rounded square case.

• Case Dimensions: Approximately 24mm to 25mm in width (excluding the crown) and 30mm to 31mm in length (lug-to-lug).  The case thickness is typically around 8.9mm to 9mm. 

• Materials: Constructed from stainless steel with an 18k yellow gold octagonal bezel secured by eight screws.  Some variations feature a full 18k gold case or a "Godron" (fluted) bracelet.

• Dial: Typically features a white, silver, or burgundy dial with black or gold Roman numeral hour markers, a minute track, and blued-steel sword-shaped hands.  Rare "ghost dial" variants exist where the numerals are subtle or faded.

• Crystal: Scratch-resistant sapphire crystal. 

• Crown: Steel crown set with a blue synthetic spinel cabochon (some sources note a faceted spinel).

• Bracelet: Integrated stainless steel and 18k yellow gold bracelet (often the "Godron" style with fluted center links) featuring a folding deployment clasp.  It typically fits wrists up to 6.25–6.8 inches. 

• Functions: Hours, minutes, and central seconds. Some versions include a date complication, though many ref. 0907 models are time-only. 

Movement Specifications

The reference 0907 is powered by an automatic self-winding mechanical movement.  While Cartier often labeled these as "Cartier Automatic," the base caliber is widely recognized as a Swiss-made ETA movement (commonly the ETA 2892-A2 or similar high-grade variant), modified and finished by Cartier. 

• Type: Automatic self-winding.

• Jewels: Typically 23 to 28 jewels, depending on the specific base caliber and modifications. 

• Frequency: 28,800 vibrations per hour (4 Hz).

• Power Reserve: Approximately 40 to 42 hours.

• Features: Hacking seconds (stops when the crown is pulled) and bi-directional winding.