Waterproof, Anti-Magnetic, Shock Resistant, 30mm Diameter Case. 10k Rolled Gold Plate Bezel & Backplate. Dial is identical to 1955 ad shown below, 1954 Commodore in comments block below, 1957 Commodore dial in the on-site database. 1959 case appears to have upgraded the lugs in comparison the 1954,1955,1957 lug style.
Fifth
The other dial you are referring to is a Clipper #30 in the ad above (below left). And the Royal Clipper #26 same dial as Clipper #30 but an X 2-tone dial (middle). Commodore dial (right). Similar but different. Notice that Instead of squares on the outer chapter of the Clipper & Royal Clipper, the unknown referred to in the above ad as #28 Commodore has numbers @ 5 minute intervals & smaller batons. The Commodore dial differs because of the 5 minute/5 second numbering on the outer circumference, throughout the 1950s the Commodore has maintained the same unique dial.
Edited for clarity 10.02.2011