Answer first: the movement and date-setting check is the top pick, because the ref. 1655 uses a slow-set 1570-family caliber, and no budget replica reproduces that behavior. You can test it with the watch in your hand, no tools and no opening of the case. This guide scores a watch against four criteria: case and lug geometry, dial and hand detail, movement and date setting, and crystal, crown, and caseback. Each criterion gets a section below with the strengths of the check, its limits, and a note on when to lean on it.

Some context before the checks. The Explorer II ref. 1655 arrived in 1971 as a tool watch for cave explorers, with a fixed 24-hour bezel and an orange 24-hour hand so a wearer underground or above the Arctic Circle can separate day from night. It stayed in the catalog into the mid-1980s. Collectors now track several dial generations, and the nickname attached to the reference is a collector convention rather than a record of the actor wearing one. That history matters here, because a replica has to fake decades of small production changes, not one fixed design.

Case and lug geometry

A genuine 1655 measures about 39 mm across, with 20 mm lugs and no crown guards. The mid-case has a distinct step where the bezel ring meets the case, and the lugs curve toward the wrist instead of dropping straight.

  • Pros: case profile is hard to fake at low cost, and a caliper plus a straight edge settles most doubts in a minute.
  • Pros: the absence of crown guards is a fast visual filter, since many generic replica cases copy Submariner-style shoulders.
  • Cons: polishing and service wear soften edges on real watches, so a worn genuine case can look wrong at first glance.
  • Cons: aftermarket cases exist on real watches, so geometry alone cannot confirm a movement or a dial.

Dial and hand detail

Real 1655 dials are matte black with printed text and an applied coronet at twelve. The 24-hour hand is orange with an arrow tip. Lume plots sit inside the hour markers and on tritium-era examples they age to a warm tone that varies from watch to watch.

  • Pros: printing weight, letter spacing, and font shape are the details replica dials get wrong most often, and a loupe makes the difference visible.
  • Pros: patina on tritium is difficult to copy in a way that looks natural under raking light.
  • Cons: dial generations differ, so a genuine Mk1 next to a genuine later dial will not match each other.
  • Cons: relumed and refinished dials exist, and a good refinish can read as a fake to a collector.

Movement and date setting

This is the check I would run first. The reference uses a 1570-family automatic with a slow-set date, meaning you advance the date by cycling the hands past midnight rather than pulling the crown to a quick-set position.

  • Pros: setting behavior is binary. Either the date snaps over with a crown position, or it does not.
  • Pros: rotor noise, winding feel, and beat rate give a second signal that a quartz or cheap automatic replica cannot match.
  • Cons: you cannot confirm matching case and movement numbers without opening the case, and that carries risk.
  • Cons: a genuine movement can sit inside a rebuilt watch, so this check proves one part, not the whole watch.

Crystal, crown, and caseback

The 1655 has an acrylic crystal, a period-correct winding crown, and a screw-down caseback with model markings. There is no cyclops magnifier over the date, which trips up buyers who assume every Rolex date window is magnified.

  • Pros: acrylic has a warm optical quality that sapphire replacements do not reproduce, and the missing cyclops is easy to confirm.
  • Cons: crystals and crowns are service parts, so replacements on genuine watches are normal and expected.
  • Cons: caseback stamping alone is weak evidence, since stamps can be copied and cases can be swapped.

Which check fits your situation

If you are standing at a table with the watch in hand and five minutes to decide, run the movement and date-setting check first, then the dial print under a loupe. If you are buying remotely from photos, work the case geometry and the missing cyclops, and treat any listing that skips movement photos as a pass. If you already own the watch and want certainty, have a watchmaker open the case and compare the movement to the reference specification. Buying or trafficking in counterfeit watches carries civil and criminal exposure in the United States, and customs officers can seize counterfeit merchandise at the border, so a cheap fake is a bad trade even before it reaches your wrist.