The most reliable fake Rolex 16600 for most buyers is a 40 mm Sea-Dweller first copy running an ETA 2836-2 or a 3135-clone automatic, with a helium escape valve that actually unscrews, a flat sapphire crystal and no cyclops, and a case that reads visibly thicker than a Submariner. Everything else is decoration. Judge a 16600 replica on six things: case and bezel geometry, valve and crown construction, dial and crystal accuracy, movement and serviceability, bracelet and clasp, and what the seller will stand behind. The checklist at the end pulls it together.
One point up front: a first copy is a replica. It is not a Rolex, it carries no Rolex warranty, and it should never be sold or passed on as genuine. This guide assumes you know that and want the best-built tribute of the 16600 reference to wear.
Case and Bezel Geometry
The 16600 is a 40 mm watch with a case that sits deeper than a Submariner. Replicas fail here first, because many builders use a Submariner mid-case and fit a Sea-Dweller dial to it. Measure across the bezel, check lug-to-lug, and study the caseback thickness in profile photos.
What works
- Case diameter close to 40 mm, checked with calipers rather than a ruler.
- A profile that is thicker than a Submariner, with a stepped caseback.
- Lugs with the correct taper and drilled or undrilled holes matching the version you want.
- A coin-edge bezel that turns with firm clicks and no back play.
Where replicas fall short
- Thin Sub-style cases that look flat beside a real Sea-Dweller profile.
- Lug width off by a fraction, which makes aftermarket bracelets fit badly.
- Insert paint that sits too fat or too thin inside the numerals.
Best for: daily wearers who will notice case shape more than any other detail.
Helium Escape Valve and Crown
The valve on the left flank at 9 o'clock is the tell. On a genuine 16600 it is a gas escape valve. On a replica it is either a working threaded valve or a cosmetic plug glued into the case.
Working valve
- Unscrews and seats again with a real gasket under it.
- Adds correct depth to the case flanks in profile.
Cosmetic valve
- Cheaper, and often pressed or glued rather than threaded.
- Can sit proud or off-center, which is easy to spot in a side photo.
Check the crown at the same time. A Trip-Lock style crown should show three dots and thread smoothly. A gritty or cross-threading crown is the first part to fail.
Best for: buyers who handle the watch before paying. A crooked cosmetic valve is a reason to walk away.
Dial, Insert, and Crystal
The 16600 dial carries printed depth text, round lume plots with metal surrounds, and a date window with no magnifier over it. That last detail matters, because a cyclops bubble is the fastest way to make a Sea-Dweller look like a Submariner.
Strengths to look for
- Flat sapphire or acrylic crystal with no cyclops, set flush with the bezel.
- Marker surrounds that are even in thickness, with lume that sits level inside them.
- Date font and wheel alignment that sit centered in the window.
- Seconds hand with the small lume circle near the tip.
Weak points
- Text printed too thick, too glossy, or spaced wrong.
- Bezel insert pearl set high and ready to catch on a sleeve.
- Lume that glows for ten minutes and then dies.
Best for: buyers who want a convincing look at arm's length rather than under a loupe.
Movement and Serviceability
This is where price differences become real. An ETA 2836-2 pattern automatic, or its Seagull equivalent, hacks, winds smoothly, and any local watchmaker can regulate it. A 3135 clone copies the genuine architecture more closely and usually arrives with better finishing and a smoother crown action.
ETA-pattern movements
- Parts and service are widely available in the US.
- Runs at 28,800 vibrations per hour with a quickset date.
- Cheaper to replace than to repair if it dies.
3135 clones
- Closer to genuine mechanics and feel at the crown.
- Fewer technicians will touch them, and parts can be scarce.
- Quality varies a lot between builders, so ask which version is fitted.
Best for: first-time buyers, the ETA pattern. Collectors of replicas who already have a watchmaker, the 3135 clone.
Bracelet, Clasp, and Finish
Rolex fitted the 16600 with an Oyster-style bracelet using a flip-lock clasp and a dive extension. Replicas often get the clasp right and the links wrong, or the reverse.
Signs of a good bracelet
- Solid end links that sit flush against the lugs with no gap or rattle.
- Screwed links rather than pin-and-collar construction on higher tiers.
- A flip-lock that snaps shut under tension and a dive extension that folds out.
Signs of a weak one
- Hollow, tinny links that kink when you flex them.
- Brushed and polished surfaces that blur into each other.
- Clasp stamped so light you can feel the edges with a fingernail.
Best for: anyone who will swap straps. Solid end links take the abuse of repeated fitting far better.
Water Resistance and Daily Wear Claims
Seller listings quote depth ratings freely. Treat those numbers as marketing until the watch is pressure tested by someone with a machine. Gaskets on replicas are the least consistent part of the build.
Reasonable expectations
- Splash and rain resistance on a well-sealed case is realistic.
- A pressure test at a local shop tells you what you actually have.
- Silicone grease on the caseback gasket helps if you plan to swim.
Unreasonable expectations
- Diving with a replica, regardless of what the listing says.
- Trusting a rating printed on a hangtag with no test behind it.
Best for: desk divers and pool swimmers who get the case tested first.
Seller Checks Before You Pay
Ask for photos of the watch you will receive, not catalog images. The valve side, the crown, the clasp code, and the caseback should all appear in the set.
- Confirm the movement model in writing.
- Confirm a return window and who pays return shipping.
- Confirm the payment method protects you if the watch never ships.
- Ask for a timing reading if the seller has a timegrapher.
Quick Checklist
- Case measures close to 40 mm and sits thicker than a Submariner.
- Helium valve unscrews and sits centered at 9 o'clock.
- Crystal has no cyclops and sits flush with the bezel.
- Dial text, marker surrounds, and date alignment look even.
- Movement is named, hacks, and winds without grit.
- Bracelet end links are solid and the flip-lock snaps.
- Seller provides real photos, a return window, and a written movement spec.
- You accept that this is a replica and will not represent it as genuine.