Short answer
Most fake Fifty Fathoms Tritium 5015s get the silhouette right and the details wrong. The case shape, the sapphire bezel and the wrist presence are easy to copy. The TRITIUM line under the logo, the tint of the lume and the movement behind the display back are not. Judge a copy on those three and you can sort the decent ones from the junk in about a minute.
What the real 5015 Tritium is
Blancpain's 5015 is the modern Fifty Fathoms. A 45mm case, roughly 15.4mm thick, 300m water resistance, a domed sapphire bezel over a lume insert, and the calibre 1315 automatic inside. That movement runs three barrels in series, about 227 parts, and a 120-hour power reserve.
The Tritium version takes that base and gives it a vintage face. Titanium case, warm cream lume instead of bright white, and the word TRITIUM printed below the Blancpain logo. It was made for collectors who wanted the look of a 1950s Fifty Fathoms on a watch they could still take diving. The lume is styled to look aged. It is not actually old.
What the replicas actually are
Nearly every copy on the market starts with a Miyota 9015 or a similar Japanese automatic, then dresses it with decorative plates and a stamped rotor meant to suggest the calibre 1315. Some sellers call that a clone movement. It is not. The case is usually 316L steel, sometimes listed as titanium, and the strap is a nylon weave that copies the sailcloth look without the texture.
Dial and lume
This is the first place to look.
- The TRITIUM line. Genuine printing is thin, even, and centered under the logo with clean spacing. Copies run heavier, slightly wide, or shifted a hair to one side.
- Lume color. The real vintage-tint lume has a soft cream tone with small variation from plot to plot. Cheap copies come out flat orange or too green, and every marker matches exactly.
- Logo and script. Letter spacing on BLANCPAIN and on the Fifty Fathoms script are the two most photographed details in the community for a reason. Look at the gap between the F and the i.
- Date wheel. The font should be thin and match the dial text. Replica date wheels tend to be bolder and sit a fraction high or low in the window.
- Hands. The sword hands have polished bevels that catch light along a hard edge. Copies show a softer, rounder bevel.
Sapphire bezel
The 5015 bezel is a domed sapphire ring over a lume insert, with the numerals and markers printed underneath. On a good copy the dome is close, the numerals carry the right weight, and the lume under the crystal has some depth. On a bad one the crystal is cloudy, the numerals look painted on top, the lume blob is uneven, and the pip sits off center. Turn the bezel too. Genuine action is firm with clean clicks. A copy usually feels loose or gritty.
Case, crown and caseback
Lug width is 23mm, which matters if you plan to swap straps. The crown guards should be crisp and symmetrical, and the crown itself carries an engraved logo that reads easily under a loupe. Caseback engraving is another divider. The genuine text is deep and sharp, while many copies show shallow laser etching with rounded edges. If the back has a sapphire window, the same rule applies as the front. Look through it.
The movement is the tell
The 5015 has a display back, so anyone can see what you bought. The calibre 1315 fills the case: three barrels, 35 jewels, a silicon balance spring, and a large rotor engraved with the Blancpain name. A Miyota-based copy shows a small balance wheel in the wrong position, a shallow movement swimming in empty space, and a rotor that is too thin with engraving that looks stamped rather than cut. No amount of decoration hides the missing depth. This is the one part of the watch a factory cannot fake well.
Quick in-hand checklist
- Read the TRITIUM line with a loupe. Weight and spacing first.
- Check lume color plot by plot. Perfect uniformity is a bad sign.
- Rotate the bezel and listen for the click.
- Compare the date font against the rest of the dial text.
- Look through the caseback and find the balance wheel. Small and off to one side means a Miyota.
- Measure the lugs if you can. 23mm, not 22.
Price tiers and what they tell you
Sellers split stock by factory and movement, and the spread is wide. The cheapest tier gets you the right shape and a dial that falls apart under a loupe. The mid tier fixes the dial and bezel but still runs a decorated Japanese movement. The top tier spends its money on the case, crystal and printing, and still runs the same movement. Ask which movement is inside before you ask anything else. If a listing cannot answer that question, that is the answer.
One honest note
A copy stays a copy. It will not hold value, it will not get service from Blancpain, and the 120-hour reserve and silicon hairspring of the real 1315 are not part of the deal. Buy it because you like the look, not because you think it is the same watch.