A "fake Rolex 1666 6" does not match any watch Rolex ever built. Rolex has no reference 1666 6. The string is either a scrambled search for the Sea-Dweller ref. 16660 or a listing title that a seller broke apart to slip past brand filters. Any watch sold under the exact text "1666 6" is mislabeled or a replica.

That matters because the reference number sets the price, the parts, and the resale value. Get one digit wrong and you are comparing two different watches.

Which Rolex Reference Was 1666 6 Supposed to Be?

Two numbers show up in search logs and marketplace titles: ref. 16660 and ref. 16600. Rolex built the 16660 Sea-Dweller from 1978 to about 1989, and collectors call it the "Triple Six". The 16600 replaced it and ran from 1989 to 2008.

The real 16660 is a 40 mm steel dive watch with a few features that replicas struggle to copy:

• 1,220 m (4,000 ft) depth rating, tested at the factory
• Sapphire crystal, thicker than the one on a Submariner
• Helium escape valve on the left case flank at 9 o'clock
• Quickset date, powered by the cal. 3035 and later the cal. 3135
• Tritium lume on period dials, which ages to a warm cream color

How Rolex Reference Numbers Work

Rolex uses four to six digits, and the numbers do not run in order. One dropped or added digit moves you to a different generation with a different movement and a different price.

• 1665: the first Sea-Dweller, late 1960s
• 16660: the "Triple Six", 1978 to 1989
• 16600: updated Sea-Dweller, 1989 to 2008
• 116600: Sea-Dweller 4000, 2014 to 2017

None of these is 1666 6. That number reads like a typo, not a watch.

Why Do Listings Use the Broken "1666 6" String?

• Filter evasion. Marketplaces block searches and listings that pair a brand name with the word replica. Sellers break the spelling or split the number to stay live.
• Typos. A dropped or extra 6 turns 16660 into 1666 6.
• Template recycling. Replica sellers copy the same listing text across dozens of models and never check the reference.

A sloppy title is the first signal. Sellers who cannot copy a reference number right are not the sellers you want grading a watch for you.

How to Tell a Replica Sea-Dweller From the Real Thing

Checks you can do in your hands

• Caseback engraving. Genuine 16660 casebacks carry a reference and case number that match the paperwork.
• Helium valve. The real valve sits on the left flank and screws down flush to the case. Fakes sit proud or sit at the wrong angle.
• Date window. The cyclops should magnify about 2.5x. Fake crystals run closer to 1.5x to 2x, and the date looks small and washed out.
• Lume. A 1980s dial should show aged tritium. Bright, uniform white lume on a watch sold as a 1980s piece is a red flag.
• Reference and serial stamps. These sit between the lugs at 12 and 6 o'clock. Factory stamps are cut deep with clean edges. Laser engraving looks shallow and flat.

Checks that need a watchmaker

• Beat rate. The cal. 3035 and 3135 run at 28,800 vibrations per hour. Many replica movements run at 21,600.
• Pressure test. A real 16660 holds 1,220 m. Replica cases often fail well short of that, and the gaskets are the reason.
• Bracelet and clasp. Ask for the clasp code and compare it with the production year. Mismatched codes point to a parts build.

What Does a Replica 16660 Cost Compared With the Real Watch?

Replica Sea-Dwellers sell in the low hundreds of US dollars, and the best "super clone" builds cost more than that. A genuine ref. 16660 trades into five figures in USD, and a full set with box and papers sits at the top of the range.

That gap is the whole reason the fake market exists. It is also why a cheap price on a "Triple Six" tells you what you are buying.

Is It Legal to Buy a Fake Rolex in the US?

Owning a counterfeit is not the part that creates legal trouble. Selling, importing, and shipping counterfeits is. U.S. Customs and Border Protection can seize and destroy parcels, and commercial trafficking in fakes falls under federal law.

What happens at customs

Overseas replica parcels get held, inspected, and destroyed. You lose the money and get a letter. Repeated seizures can lead to fines.

Frequently Asked Questions

Is there a real Rolex reference 1666 6?

No. Rolex reference numbers run four to six digits, and 1666 6 is not one of them.

Which reference number is closest to 1666 6?

Ref. 16660, the Sea-Dweller made from 1978 to 1989, and ref. 16600, made from 1989 to 2008.

Where is the reference number on a Sea-Dweller?

Between the lugs at 12 o'clock, visible once you take the bracelet off. Later Rolex models also engrave it on the inner bezel ring.

Can a jeweler spot a fake 16660 from a real one?

Yes, with the caseback removed. Movement finish, beat rate, and gasket quality are the fastest tells.

Before You Buy

Ask the seller for a photo of the reference stamp and a clear shot of the movement. Check the reference against Rolex's own model history. If the title reads "1666 6" and not "16660", treat the rest of the listing as unreliable too.