Omega 2640

The Omega Reference 2640 is a classic time-only wristwatch produced primarily between 1949 and 1958, though examples with movement serials dating to 1959 exist. Its significance lies in its notably large case size for the era, around 36mm, earning it the “Jumbo” nickname among collectors. This substantial size, often housed in a robust stainless steel case with a screw-down back, offered greater wrist presence than typical 1950s dress watches and bridged the gap towards sportier styles. Key features include the reliable Omega Caliber 283 (or occasionally Cal. 285) manual-wind movement from the respected 30mm family, featuring center seconds (denoted by the “SC” suffix in many references like 2640-5SC or 2640-7SC), and a wide variety of dial designs, including silver, white, cream, and textured options like honeycomb or “Explorer” layouts. Its blend of elegant design, versatile sizing, and robust mechanics makes it an appealing and collectible vintage Omega.  

Specifications

Variations and Key Features

The Omega Ref. 2640, produced mainly in the 1950s, offered a range of styles built upon its characteristic “Jumbo” case and reliable manual-wind movement.

Case:

• Shape & Size: Distinctive for its larger-than-average size for the era (35-36.5mm), often referred to as “Jumbo”. The case shape is typically round with elegant lug designs.  
• Lugs: Often featured distinctive faceted or “Bombay” style lugs, adding character.  
• Materials: Primarily stainless steel. Variations included a two-tone model (Ref. 2640-61 SC) with a gold-plated bezel and examples with solid 14k rose gold lugs (Ref. 2640-7SC).  
• Construction: Commonly featured a screw-down case back for enhanced durability and water resistance (original rating 30m).  
• Crown: Original examples feature a winding crown signed with the Omega logo.  

Dial:

• Colors & Textures: Wide variety offered, including Silver (matte/satin), White/Grey, Sand/Champagne, and Cream. Textured options like Honeycomb were also available. Natural patina is common and often appreciated.  
• Hour Markers: Typically applied indices. Styles included faceted Dagger shapes , simple Baton styles , or Arabic numerals.  
• “Explorer” Dial: A notable variation features Arabic numerals at 3, 6, 9, and 12, with other hours marked by dagger/triangular indices.  
• Marker Material: Indices could be steel or have warmer gold/gilt tones.  
• Text: Standard text included an applied Omega logo, printed “Omega” name, and “Swiss Made” or “Switzerland” at the base.  

Hands:

• Styles: Common styles included elegant Dauphine or Sword hands.  
• Seconds Hand: A defining feature was the center sweep seconds hand (denoted by “SC” in the reference). This hand sometimes appeared in a contrasting red color.  
• Lume: Some variants featured luminous material (likely Radium) on hands and hour markers for low-light visibility.  

Crystal:

• Material: Domed Acrylic (Plexiglass) crystal.  

Movement (Caliber 283 / 285):

• Type: Manual-winding, 17-jewel movements from Omega’s highly regarded 30mm family.  
• Performance: Known for robustness, reliability, and accuracy. Beat rate of 18,000 vph, power reserve approx. 45 hours.  
• Functions: Time only with center sweep seconds hand.  

Reference Suffixes:

• -X: Numerical suffixes (e.g., -4, -5, -7, -8, -9, -61) likely denote minor sequential production variations in case, dial, or other details.  
• SC: Denotes “Seconde Centrale” (Center Seconds), highlighting the sweep seconds hand driven by the Cal. 283/285 movement.  

Additional Information

Historical Context: The Omega Ref. 2640 was produced during Omega’s “Golden Era” (1950s-1960s), a time when the brand launched iconic lines like the Seamaster, Speedmaster, Railmaster, and Constellation. The 2640, with its classic design but larger “Jumbo” size, offered a versatile option that blended dress watch elegance with a more substantial, modern presence, distinct from both the smaller dress watches and the dedicated tool watches of the era.  

Movement Significance: The use of the Caliber 283 (or 285) placed the Ref. 2640 firmly within Omega’s tradition of high-quality watchmaking. The 30mm movement family, from which these calibers derive, was renowned for its performance in chronometer trials and its overall durability, ensuring the 2640 was not just stylish but also mechanically sound.  

Collectibility: The Omega Ref. 2640 is a desirable vintage model due to its “Jumbo” size (appealing to modern tastes), the reliability of its movement, and the wide variety of available dial styles. Its relative scarcity compared to round Seamasters or Constellations from the same period adds to its appeal. Condition, originality (especially of the dial and lume), and specific dial variations (like Explorer or Honeycomb dials) are key factors influencing value in the collector market.