We see three different production batches, with all Mido’s one-piece case to eliminate water leakage at the back of the watch, and was tested to a depth of 300m/1000 feet (I have not found any reference to testing of these depths with the cork seal). The watch is a patented Bernard Taubert (15 June 1960 (Patent No. CH346175)) front-loading (with the movement placed in the case before the crown and winding stem is inserted) design, requiring a special Mido Ocean Star tool to remove and fit the crystal, a system known as “Permalift”.[1] For those looking, these Mido Ocean Star tools may still be found reasonably easily on eBay, and were designed and patented by Taubert as well. [3]
Paired with this case is the “Aquadura” cork sealing system, which was Mido’s successor after the Taubert & Fils corked-sealed winding stem patent (Brevet No. 130942, 1928) expired. [2] It appears that Mido claims to have the patent on the cork seal in 1934, though this follows Taubert & Fils, and curiously Mido shows an image from the Taubert patent on their Mido history web page.
The case measures 38mm across all patches, 45mm lug to lug. Each production period has some standard configurations of case plus other features (dial color, unit of measurement (metres or feet), tension ring color, lume plots on the tension ring, etc.) though there are so many different variations in the Mido ref 5907, it is reasonable to assume that this list may change as more are found.
Mk 1 (1959-62):
First production batch
Serial number located between the lugs
No reference number or serial number stamped on caseback
White dial
No date window
Gold hour and seconds hand (always with white dials)
Non-luminous hour index marks, numerals in center circle, and center plots
Black or white tension ring, with or without lume plots
Inside caseback:
Mido
LIMITED
OCEAN-STAR
SWITZERLAND
VACUUM
D+58461
RUSTLESS
STEEL
Mk 1 Transitional (1962):
Second production batch
Reference number is stamped on caseback
Black dials first appeared in this batch
Date window first appeared in this batch
Silver hour and seconds hand
White tension ring
Inside caseback:
[no image available]
Mk 2 (1962-65):
Last batch
Serial number and reference number are stamped on caseback
Predominantly white dials
Date window
Inside caseback:
Mido
LIMITED
OCEAN-STAR
SWITZERLAND
VACUUM
PATENT
RUSTLESS
STEEL
[1, 2] Mido Watches: Part 2, C.1955-2000, The Watch Forum
[3] FRANÇOIS BORGEL, LOUISA BORGEL, AND THE TAUBERT FAMILY, NAWCC (2013)