Answer first
The 5000 in "Fifty Fathoms 5000" is a Blancpain reference number, not a depth rating. It covers the Fifty Fathoms Bathyscaphe Automatique family: a 43 mm steel dive watch, 300 m water resistance, in-house calibre 1315. A fake Fifty Fathoms 5000 is any watch that copies that design without coming from Blancpain. Replicas run from rough quartz models under $80 to "super clone" builds that copy the case shape, dial printing and decorated movement. The details that separate a good replica from a bad one are the same details that separate a replica from the genuine watch: case thickness, date position, bezel action, lume, engraving, and power reserve.
Genuine reference points to memorize
- Case diameter 43 mm on the standard Bathyscaphe, thickness about 13.4 mm.
- Water resistance 300 m (30 bar). Fifty fathoms equals about 91.4 m, the rating of the 1953 original.
- Movement calibre 1315, automatic, three barrels, roughly 120 hours of reserve.
- Date window at the 4:30 position.
- Unidirectional bezel with a sapphire or ceramic insert and firm clicks.
How to check a Fifty Fathoms 5000 replica, step by step
- Measure the case with calipers. A 43 mm diameter within 0.3 mm is acceptable. Anything past 15 mm thick is a giveaway, because the genuine watch sits near 13.4 mm.
- Look at the date window. It must sit at 4:30. A 3 o'clock date means the builder used a stock Miyota or Seiko movement and printed a Bathyscaphe dial on top.
- Turn the bezel through a full rotation. Count the clicks and feel for back play. A loose bezel with mush between clicks is low tier work.
- Charge the watch, set it down, and check it after 24 hours. A clone of calibre 1315 should still run past day three. A 40 hour movement in a decorated case back is the most common shortcut.
- Examine the caseback engraving under a loupe. Genuine engravings are crisp and shallow with clean edges. Laser etched replicas look sandy and rounded.
- Check the lume in a dark room. Apply a UV light for 30 seconds first. Weak, uneven glow with a green cast points to cheap paint instead of a proper compound.
- Weigh the watch on a kitchen scale. A steel Bathyscaphe on a bracelet lands in a narrow range. A watch that feels light usually has a hollow case or an alloy bracelet.
- Inspect the crown threads. Screw the crown down and feel the engagement. Gritty threads and a crown that stops short of the case signal a cheap tube.
Quality tiers you will see
Entry replicas use a quartz or basic automatic movement, a mineral crystal, and printed indices. Mid tier builds add a sapphire crystal, a ceramic bezel insert, and a 9015 based automatic with a date at 4:30. Super clone builds copy the case profile, the dial texture, the hand shape and the movement decoration, and often run within a millimeter of the genuine dimensions. None of them match the three barrel architecture or the silicon balance spring of calibre 1315.
What no replica reproduces
Case finishing is the hardest part to copy. Blancpain polishes and brushes the Bathyscaphe case in separate planes with sharp transitions. Most replicas soften those lines. The sapphire bezel insert, the depth of the dial printing, and the movement architecture are next on the list. Treat any listing that claims a one to one copy of calibre 1315 as marketing text.
Before you pay
Ask for caliper photos, a timed power reserve test, and a close photo of the caseback. Compare those against the genuine specifications. If a seller cannot supply all three, walk away regardless of the price.