Here we have a clean, clear and classic WW2 period Omega military style tool watch. The design of the case is highly unusual and not commonly seen. The movement, crystal, case back and winder sit within one tightly sealed group that press fit into the front of the case. The front frame consists of the bezel, sides and lugs. This is an intriguing example of waterproof design for a robust military style tool watch. Such a design was later patented by the Swiss brand Roamer in the mid 1940s, but this watch demonstrates that Omega were the early innovator. 
The silver dial is clean and classic with the detailed minutes/seconds track to 1/5th seconds graduations. The black Arabic numerals are clear and defined, with the Omega logo and signing below 12. The thermally blued plume hands provide a contrast against the dial, with the central second hand. 
The steel case is compact with the water-resistant domed crown to the right.
Inside it is signed the Omega logo and serial number. The movement is an Omega calibre 17.8 SC which has been recently serviced and is keeping time to within 1 minute variation a day.
 
The case design is an early water-resistant innovation. The rear section comprises of the solid case back with movement and dial within, with the crystal sitting tightly over the surround. The crown is also part of this section. To expose the inside of the case the split stem crown is removed, with the crystal lifted off. Once a chapter ring around the dial is removed, the dial and movement can be accessed. 
This section is a friction push fit into the front section. This section has the bezel, sides of the case (with crown cut out) and the lugs. The strap attaches with drilled lug holes. 
This design ensures a tight seal around the crown and crystal which would improve water resistance. 
Other examples of this case variation can be found but are often poorly listed without recognition of the ingenious case design. Omega also make no mention of the design throughout their history. 
 
The case is compact measuring 30.5mm wide x 30.7mm long, with the crown taking the width to 33.9mm. The lugs add to the presence of the case with the total lug-to-lug measurement sitting at 38.25mm. The case depth of 8.75mm makes this a slim and comfortable wear. The notched bezel has the polished crystal surround with the bevelled edge that catches the light. The lugs are well sized with the tapered and downturned design. They have the brushed finish to the top, with the polished bevel. The sides are also brushed. The case back has the circular brushing with the sunburst finish. 
The inside of the case has the perlage finish and is marked as Stainless steel, with the Omega logo and serial number dating it to 1942. 
 
The silver dial is clean with the clear black signing and bold Arabic markers. The detailed 1/5th seconds track sits around the outside for precise time keeping. The hour and minute hand are of Plume style, which in our eyes is one of the most attractive styles found on 1930s/40s Omegas. With the bright thermally blued finish the hands are a joy to look at, whilst providing a clear contrast against the dial. The central second hand has the tear drop counterbalance with the sharp, thin design. 
 
The movement is the Omega calibre R17.8 SC. It is a 16 jewel manual wind movement which was launched in 1939. It has a higher than average frequency of 21,600 BPH, with a 45 hour power reserve. It has been recently serviced and is keeping time to within +50 seconds a day. It has an amplitude of 250 degrees and a beat error of 0.7m/s.
 
The watch is modelled on a 7” wrist circumference.
Full condition report below. Please see the images as these compliment and aid the description provided below.
 
Dial:
The dial is original. It is a silver tone which has developed a bubbled patination with age. This is noticeable to the centre of the dial and around the right-hand side. It has light scratching with a couple of larger marks that catch the light as they expose the metal base of the dial. The signing is good and clear. The omega logo is slightly worn but still defined.
 
Hands:
The hands are original and are of Plume style. They are in good condition with the bright thermally blued tone. The central second hand is original and has developed a purple oxidised tone with age.
 
Glass:
The crystal is original and is in good condition with only light marking.
 
Crown:
The crown is a well-matched replacement which is in good condition, sealing tightly.
 
Case:
The case is stainless steel. The front section has some light marks associated with age. The brushed and polished finishes have been lightly re-done to bring the best out of the case, without a loss of material.
The solid rear piece sits in tightly and is in good condition with the brushed sunburst. 
 
Strap:
The watch comes on a vintage genuine leather strap which is in good condition.
 
Movement:
The movement is an Omega Calibre 17.8 SC. It is a manual wind movement with a jewel count of 16 and a frequency of 18,000 BPH.
 
The movement has been recently serviced and is running well and keeping time to within +50 seconds a day. It has an amplitude of 250 degrees and a beat error of 0.7m/s.
 
Case Dimensions:
Case width: 30.5mm
Case width with crown: 33.9mm 
Case length: 30.7mm 
Case length lug to lug: 38.25mm
Case Depth: 8.75mm
Lug width: 15.5mm