The short answer: a search for this string points to a first copy of the Blancpain Fifty Fathoms, and the four digits at the end are a seller listing code rather than an official reference. The version worth your money is the 5015 style at about 45 mm, with a sapphire bezel insert, a domed sapphire crystal, and a Swiss clone automatic such as the ETA 2824 pattern or the Sellita SW200. Those details carry most of the look and all of the reliability. The guide below explains the string first, then ranks three versions and gives you a check list you can run against any listing.
What the search string means
Three parts sit in that phrase. "Fake" is the word buyers type for a first copy or replica. The single letter is the factory shorthand sellers use, and the letter changes as workshops open, close, and rename themselves. "Fathoms" is the Blancpain Fifty Fathoms, launched in 1953 and one of the founding modern dive watches. The trailing number is the part people misread. It is the seller's own stock code for one specific configuration, so two sites can use the same number for two different watches.
That last point matters. If you shop by number alone you can end up with a 43 mm case when you wanted 45 mm, a mineral bezel insert when the photos showed sapphire, or a low beat movement instead of a high beat clone.
Top pick: the 5015 style Fifty Fathoms
The 5015 look is the one most people picture when they say Fathoms: a wide bezel with a domed insert, a thick case with pronounced crown guards, broad arrow hands, and a large luminous chapter. A good first copy of it reads right from arm's length, which is the whole point of the exercise.
Pros
- Case profile and crown guards match the silhouette people know
- Sapphire bezel insert keeps its gloss and takes scratches better than mineral or printed glass
- Common movement pattern, so service and parts are easy to find
- Works on sailcloth, rubber, leather, and steel
Cons
- 45 mm wears large on a wrist under about 17 cm
- Case height stacks under a tight shirt cuff
- Weak lume on cheaper builds is the first thing that gives them away
Best for: someone who wants the classic big dive watch look and has the wrist to carry a large case.
Option two: the Bathyscaphe style
The Bathyscaphe is the slimmer branch of the family, with a cleaner dial and a case around 43 mm. In first copy form it is the more comfortable watch, and the easier one to wear to an office or a dinner.
Pros
- Smaller case sits flat and slips under a cuff
- Simple dial with fewer oversized markers, so finishing flaws hide better
- Brushed surfaces show fewer smudges and swirl marks
Cons
- Less of the big dive watch drama
- Fewer sellers stock it, so you have less to compare against
- Date window placement shifts between builds
Best for: daily wear, smaller wrists, and anyone who wants one watch that covers work and weekend.
Option three: the vintage 1953 style
This is the smaller, warmer take on the design, with a domed crystal, drilled lugs, and a dial that copies the early military issue look.
Pros
- Lighter on the wrist than the 5015 style
- Period details make it a conversation piece
- Pairs well with a plain leather or NATO strap
Cons
- Acrylic crystals scratch and need polishing
- Smaller cases can look undersized on a large wrist
- Fewer strap widths fit the narrower lugs
Best for: buyers who already own a modern diver and want something with a different mood.
The four checks that decide quality
- Bezel insert. Ask which material the insert uses. Sapphire or ceramic keeps depth and color. Mineral and printed glass look flat within a month.
- Movement. Ask for the calibre name and the beat rate. The ETA 2824 pattern and the Sellita SW200 clone run at 28,800 vibrations per hour. A 21,600 movement in a dive watch is a step down.
- Crystal and coating. Domed sapphire with inner anti reflective coating. A heavy blue tint across the dial is a tell.
- Lume. Ask for a photo in a dark room. Patchy or dim glow is the fastest giveaway on the wrist.
Sizing and daily wear
Measure your wrist before you pick a case. A 45 mm case with long lugs needs a wrist of about 17 cm or more to sit without overhang. The 43 mm Bathyscaphe style fits most wrists from 16 cm up. Check the lug width too, since a 23 mm lug limits your strap choices. On water resistance, treat any claim as marketing unless the listing names a tested rating, and keep replica watches out of the pool and the shower.
Bottom line
Pick the 5015 style first copy if you want the recognized Fathoms silhouette, a sapphire bezel, and a high beat automatic. Pick the Bathyscaphe style if comfort and a smaller case matter more. Pick the vintage style if you want character over presence. Whichever you choose, buy from a seller who will answer the four questions above with specifics, because the answers tell you more than any photo.