The IWC Aquatimer Replica was the first version of this watch. It had a large coronet with a foot rounded on Rolex's R. The dial's bottom was marked with T SWISS.

The MK2 dial is similar to that of the IWC Aquatimer Replica. Collectors have given this coronet the name Frog Foot because it is more splayed and has heavier dots at the tips. It can also be found on the Rolex Explorer reference. 1016). Another big difference is in the spacing between the words PERPETUAL. The MK2 is smaller than the IWC Aquatimer Replica; the top of the L aligns with the bottom stroke of the X of ROLEX. (On the IWC Aquatimer Replica, the A of PERPETUAL was below the X). The MK2 has a T SWISS on the bottom edge, which indicates the use of tritium.

The MK3 is a noticeable difference due to the Rail Dial, as it's called by collectors. The MK2 coronet is wider, more defined and symmetrical. The outer edge is still marked with T SWISS. The text SUPERLATIVE OFFICIALLY CERTIFIED in the lower half of the dial gives away the MK3. The vertical alignment of the letters C in CHRONOMETER OFFICIALLY CERTIFIED creates a vertical gap between the two lines. It is also seen on some references. 1665 Sea-Dwellers.

The MK4 has a coronet that is narrower and taller than the MK2. The text alignment for the letter L is identical to the MK2. This change is most visible at the bottom of the dial where it reads in serif typeface T SWISS 25 T. This meant that the tritium paint used to paint the hour markers emitted less than 25mCi.

The MK5 was the last dial produced for the 1655. It had the TSWISS 25 T on the dial's bottom edge, but no serifs. The coronet was also narrower, with a larger opening in the oval below the coronet. This reminded me of the coronets of the Maxi-dial Submariner reference. Replica Panerai Luminor Submersible Watches).

There were, as mentioned above, also variations in the bezels throughout the production run. Four production versions were available, and there is also a service model. Here is the breakdown of bezels:

The IWC Aquatimer Replica is a thick font, with numeral edges that are very close to bezel inner edge. These were used for watches with IWC Aquatimer Replica or MK2 dials.

The MK2 has a thick font with the numbers centered. Some IWC Aquatimer Replica watches have this font, but it is more common on MK3 or MK4 dials.