What "fake rolex 1666 6" Actually Refers To

1666 6 is not a valid Rolex reference number. It is a dropped-digit version of two real ones: 16660, the Sea-Dweller 4000 launched in 1978 and nicknamed the Triple Six, and 16610, the Submariner Date built from 1989 to 2010. Searches for that string almost always mean one of those two watches, and the person searching wants to know whether the example in front of them is real. The short answer: a 16660 or 16610 offered as an authentic Swiss watch at a small fraction of market price is a replica. The tells are physical, not verbal.

Before You Start

  • A 10x jeweler's loupe
  • Digital calipers
  • A bright, angled light source
  • The asking price and any service history in writing

How to Inspect a 16660 or 16610

  1. Measure the case with calipers. Both references are 40 mm across, and both use a 20 mm lug width. A 42 mm case sold as a 16610 is a different watch or a replica.
  2. Measure case thickness. A 16610 runs about 12.5 mm. A 16660 runs about 15 mm because of the deeper caseback needed for its 1,220 m depth rating.
  3. Check the left case flank. A genuine 16660 has a helium escape valve at 9 o'clock. A 16610 has no valve at all. Replica sellers mix these details up often.
  4. Turn the bezel through a full rotation. A genuine bezel gives 120 even clicks with no back play and no gritty spots.
  5. Look at the dial print through the loupe. Genuine text sits on a single flat plane with sharp serifs. Replica dials show raised, rounded, or uneven paint and misaligned coronet tips.
  6. Check the date window and cyclops. The magnifier on a genuine crystal gives 2.5x and the date sits centered behind it. Replicas run under 2x or place the date off center.
  7. Open the caseback with a qualified watchmaker present. A 16610 should hold a calibre 3135. A 16660 holds a 3035 in early examples and a 3135 in later ones. Any ETA or Chinese clone movement ends the discussion.
  8. Read the engravings between the lugs. The reference number sits at 12 o'clock and the serial at 6 o'clock. Genuine engravings are crisp and even, with no tool chatter around the characters.
  9. Match the serial range to the reference and production year, then match both to the paperwork.
  10. Ask the owner to remove the bracelet or have a watchmaker pull it. Replica mid-cases often have mismatched lug hole depths and rough finishing inside the lugs.

Red Flags That Settle the Question

  • Price far below the market range for that reference and year
  • A seller who refuses an inspection by a watchmaker of your choosing
  • Photos only, with no serial number visible
  • Claim of "Swiss made" on a watch with a plastic or loose bezel insert

What To Do Next

Take the watch to a Rolex-authorized watchmaker or an independent appraiser who handles vintage sports models. Ask for a written statement that covers the reference, the movement, and whether the parts are original to the case. If the watch turns out to be counterfeit and you bought it, keep the listing, the payment record, and the messages. Buying and selling counterfeit goods is illegal in the United States, and shipments can be seized at the border. Treat the authentication report as the only answer that matters, not the seller's story.