Bulova Ambassador 30 Jewel micro-Rotor 12EBACD SS M5/M4 reference 508
Case Dimensions and features:
- Width w/o Crown: 37.45 mm
- Length: 39.90 mm
- Depth: 5.60 mm wo/crystal, 9.05 mm w/crystal
- Lug Width: 18.70 mm
- Crown: 3.95Dia mm, recessed and signed
- Crystal: 32.85Dia mm, in bezel. Flanged to be inserted from under bezel. Shallow Domed, Acrylic.
- Bezel O.D.: 34.95Dia mm
- Case Inside Diameter, first step (bezel): 32.45 mm
- Case Inside Diameter., third step (movement): 30.10 mm
- Dial O.D.: 30.25 mm
Inside case back inscriptions: Stainless Steel; Swiss; "C.B" (in box with round top); "508" (in rectangle); M4; a faint watchmaker inscription. In Ink: A “star” preceeding “764” . Feature of outside case back: Raised athletic woman dancing, as a medallion. Movement: 12EBACD Automatic Micro-Rotor 30 Jewel, Date. Engraving on Movement: BULOVA WATCH CO; 12EBACD; M4; Swiss; 30 Jewels. Under Balance Wheel: Upper case “D”
Notes: I have a number of micro-rotor Ambassadors, though I haven’t shared them all on MyBulova yet. This is my first example of this model. The date code on the inside of the case is M4, and the date code on the movement is M5. There is no serial number. I deduce therefore that it was produced in 1965. I have seen this mismatch frequently with vintage Bulova. Generally it is consecutive years, but occasionally the gap is more than a year. The circumference of the bezel has a very slight flat on one side. I re-attached it at six o’clock, but now I think it is intended to create a little distance from the recessed crown, at three o"clock. As it is, it still has close to a mm of clearance.
