If you are sorting through fake Blancpain dive watches, the version that holds up best in the hand is the Fifty Fathoms Automatique 5015 pattern with a sapphire bezel insert and an automatic movement built on the 1315 layout. It wins on the three points that decide everything else: bezel material and action, case thickness and profile, and dial printing. The criteria below apply the same test to the Bathyscaphe and to older Fifty Fathoms references.
One note before the details. Selling counterfeit watches is illegal in the United States, and imports are subject to seizure. Read this as buyer education, not a shopping list.
Tier Vocabulary: Cheap, Mid, and High-End Fakes
Listings almost never describe build quality, so the useful split is by construction. The low tier uses plated brass or pot metal, glued bezel inserts, and quartz or basic automatic movements. The mid tier moves to 316L stainless steel, a screw-down caseback, and a dependable Japanese or Chinese automatic. The high tier copies case geometry with care and uses a sapphire crystal plus a ceramic or sapphire bezel.
Strengths
- Low tier: minimal cost if you only want the silhouette on a wrist.
- Mid tier: steel cases take a polish, and movements can be regulated.
- High tier: correct proportions, sapphire glass, and bezel inserts that resist scratching.
Weaknesses
- Low tier: plating wears through at the lugs, and gaskets are often cosmetic.
- Mid tier: case thickness and crown guards still read wrong next to a real watch.
- High tier: the price climbs toward genuine entry-level divers with a real warranty.
Use case: for a travel or beater watch you expect to scratch, the low tier is the honest pick. For anything that will be seen up close, only the high tier gets near the mark.
Criterion One: Bezel Insert and Action
Current Fifty Fathoms and Bathyscaphe references use sapphire or ceramic inserts rather than the printed aluminum found on budget divers. Turn the bezel. A real one ratchets in one direction with crisp steps and no lateral play. Fakes wobble, click softly, and often rotate both ways.
Strengths
- Sapphire and ceramic inserts hold their color and resist scuffs.
- A tight ratchet is the fastest tell to check in person.
Weaknesses
- Printed inserts fade and chip within months.
- Lume pip placement is frequently off center on fakes.
Use case: if the bezel moves freely in both directions, walk away regardless of the rest of the watch.
Criterion Two: Case Profile and Thickness
The Automatique is a large, tall watch at roughly 45 mm across, while the Bathyscaphe family is slimmer and comes in 43 mm and 38 mm sizes. Replicas tend to add a millimeter or two of thickness, which changes how the watch sits and how the lugs meet the strap.
Strengths
- Accurate cases accept standard strap widths and genuine-style spring bars.
- Correct lug curvature keeps the watch from standing off the wrist.
Weaknesses
- Thick cases push the crown into the back of the hand.
- Polished chamfers are often rounded off instead of crisp.
Use case: small wrists should look at the 38 mm Bathyscaphe pattern, since the 45 mm Automatique reads oversized even when the case is correct.
Criterion Three: Dial, Hands, and Lume
Look at the script logo, the depth rating text, and the date window position under a loupe or a phone camera zoom. Fakes show heavy printing, wrong letter spacing, a glossy dial where the original is matte, and a date wheel that sits off center. Charge the lume with a flashlight and time it.
Strengths
- Good replicas get marker alignment and hand shape close.
- Applied markers with polished edges catch light the way the original does.
Weaknesses
- Cheap lume fades in twenty minutes.
- Date fonts rarely match, and magnification is often wrong.
Use case: if you photograph watches for listings or forums, dial printing is the first thing viewers will catch, so weight it above movement decoration.
Criterion Four: Movement and Caseback
Blancpain builds its own calibers, including the 1315 with a long power reserve and a free-sprung balance. Replicas use Miyota, Seagull, or decorated Chinese automatics. Open the caseback and check the rotor engraving, the finish under the rotor, and whether the balance is free sprung or fitted with a regulator arm.
Strengths
- Miyota-based builds run reliably and can be serviced by independent watchmakers.
- Caseback engraving on the high tier is often laser accurate.
Weaknesses
- Decorated plates hide unfinished bridges.
- No replica movement has a factory parts channel.
Use case: buyers who plan to keep the watch for years should favor a movement any local watchmaker will touch, which usually means a Miyota or a standard ETA clone.
Criterion Five: Water Resistance and Real Diving
Do not dive with a fake. Genuine Fifty Fathoms watches are rated to 300 m, and that rating depends on tested gaskets, threaded crown tubes, and a sealed caseback. Replicas are assembled without pressure testing, so a pool swim can flood the movement.
Strengths
- Some high-tier cases accept a pressure test at a local shop.
Weaknesses
- Untested seals fail without warning.
- Water damage voids any seller warranty you might have.
Use case: for actual diving, buy a rated dive watch from a brand with a service network. Keep replicas on land.
Legal and Practical Reality
U.S. Customs can seize counterfeit watches at the border, and trafficking carries criminal exposure. There is no warranty, no parts support, and no resale market you can use in the open. If a seller claims a replica is genuine, that is fraud, and you have no recourse.
A Quick Inspection Order
- Turn the bezel and feel the clicks.
- Measure case thickness against published specs.
- Zoom on the dial script and date window.
- Check the balance and rotor engraving.
- Assume no water resistance until a test proves otherwise.