How to Spot a Fake Fifty Fathoms 38mm
A fake Fifty Fathoms 38 mm fails on measurement first: the case runs wide, the bezel clicks with back play, and the dial printing shows ink spread under a loupe. Work through the checks below in order, from calipers to timegrapher, and stop at the first mismatch. The 38 mm line, including the Bathyscaphe ref. 5100, carries the calibre 1150, so movement finish is the hardest detail for a replica to reproduce.
Tools You Need
- Digital calipers with 0.01 mm resolution
- 10x loupe
- Jeweler's scale
- Timegrapher
- Reference photos of the exact reference number
Inspection Steps
- Measure the case diameter across the bezel at 3 and 9 o'clock with calipers. A genuine 38 mm case reads 38.0 to 38.2 mm; fakes land at 38.6 mm or wider.
- Measure the lug width and compare it with the published spec for the reference. A mismatched lug width means the case did not come from the same tooling.
- Weigh the watch head and compare the figure with owner-reported weights for the same reference. Low weight points to a thin caseback and a hollow bezel assembly.
- Turn the bezel through a full rotation. Count 60 firm clicks with no back play and no free travel; a 120-click or mushy action is a replica tell.
- Loupe the dial at 10x. Confirm that printed text has sharp edges, applied indices sit level, and the chapter ring aligns with the markers.
- Inspect the date window. Beveled edges, centered font, and a clean cut separate a genuine dial from a stamped copy.
- Check caseback engraving depth and serial format against reference photos of the same reference number. Shallow lasering and a wrong font are common on fakes.
- Unscrew the crown. Genuine crowns carry the correct signature and engage in about 2.5 turns; a rough or short thread is a mismatch.
- Examine the movement through the display back. Calibre 1150 shows Geneva stripes, blued screws, and a specific balance cock shape; clones use different perlage and a regulator index of another shape.
- Run the watch on a timegrapher in six positions and compare the rate spread with the maker's spec. A wide spread with low amplitude signals a clone movement.
Red Flags in a Listing
- Only stock photos, with no macro shot of the dial or movement
- Price far below the going rate for the reference
- Seller refuses a photo of the caseback serial
- Bezel described as 120-click
- Case thickness quoted as an approximation instead of an exact figure
What a Replica Cannot Copy
Case finishing between the lugs, the tension of the bezel spring, and the perlage under the balance cock are the three areas where replicas show their hand. Photograph each area at 10x and compare it with a known genuine example of the same reference. Store the images next to the serial number; a documented inspection beats a memory of the listing.