Short answer

The Rolex Sea-Dweller 16600 is a 40 mm dive watch. Rolex rated it to 1,220 m (4,000 ft). It carries a helium escape valve on the left case flank, a sapphire crystal with no magnifier, and the caliber 3135. Production ran from 1988 to 2008. Replica versions of the 16600 copy the dial, the case shape, and the bezel. Most fall short on case height, valve construction, crystal shape, and movement.

Reference specs

  • Case: 40 mm stainless steel, Oyster case, screw-down crown
  • Depth rating: 1,220 m / 4,000 ft
  • Movement: Rolex caliber 3135, 31 jewels, 28,800 vph, quickset date
  • Crystal: sapphire, flat profile, no cyclops over the date
  • Bezel: unidirectional, 60-minute scale, aluminum insert
  • Dial: "Sea-Dweller" and the depth rating below the hands. No "Date" line.
  • Bracelet: Oyster 93160A, Oysterlock clasp, Fliplock dive extension
  • Years: 1988 to 2008. The Deepsea Sea-Dweller 116660 replaced it.

Details to inspect on a replica

Case height. The genuine 16600 case measures about 15 mm thick. Many replicas measure 13 mm to 14 mm. The genuine case back is flat and thin, and the mid-case carries the depth. A slim replica shows this on a caliper and on the wrist.

Helium escape valve. The genuine valve at 9 o'clock is a threaded, functional part with a gasket. On most replicas it is a sealed plug with no gas path. A sealed plug still holds water out at the surface, but the part is cosmetic.

Crystal. The genuine sapphire sits close to the bezel and has a flat top with no magnifier. Replicas use mineral glass or sapphire with the wrong edge thickness and the wrong dome.

Dial text. Check font, line spacing, and the depth rating text. Early dials read "Swiss - T < 25" with tritium lume. Later dials read "Swiss Made" with Super-LumiNova. A replica that pairs tritium text with modern lume is wrong for the reference.

Bezel insert. The 16600 insert is aluminum. A ceramic insert belongs to later references, not this one. Check the numeral font and the marker at 12 o'clock.

Movement. The genuine caliber 3135 beats at 28,800 vph. Replicas run Asian clones: 2813 at 21,600 vph, 2824 and 2836 clones at 28,800 vph, or a decorated clone 3135. A timing app and a close look at the second hand sweep show the beat rate.

Weight and bracelet. The genuine watch on the full bracelet weighs about 150 g. Replicas run lighter. Check the clasp stamp, the Fliplock extension, and the fit of the end links against the case.

Service and upkeep

Clone movements take parts for their base caliber. A watchmaker who services ETA-style movements can clean, oil, and regulate them. Gaskets and seals decide water resistance. Do not assume a replica is dive rated. Pressure test the watch before any water contact.

Legal note

In the US, trafficking in counterfeit goods is a federal offense under 18 U.S.C. 2320. U.S. Customs and Border Protection can seize shipments at import. A replica carries no Rolex warranty and no Rolex service support.