The top pick for most buyers is a slim case build on a Miyota 9015 base with a correctly spaced two window date, because it comes closest to the reference thickness and any local watchmaker can service it. The three criteria that decide everything else are case profile against the original numbers, the geometry of the double date aperture, and whether the movement is a known caliber you can source parts for. Skip the rest of the shopping until those three are settled.
What the 5050 Reference Actually Is
The 5050 belongs to the modern Fifty Fathoms family, the line Blancpain built around a 45 mm cushion case, a unidirectional rotating bezel, and a sapphire crystal with a pronounced dome. The 5050 designation is tied to the Grande Date layout, where the date is read through two apertures instead of one window. That single detail is where most fakes fall apart, because a double date display needs an actual module or a modified movement rather than a printed dial.
Before you compare anything, open the manufacturer reference page and write down four figures: case diameter, lug to lug, total thickness, and the exact position of the date apertures. A replica can look right in a phone photo and still run 2 mm thick, which changes how the watch sits on a seven inch wrist and how it wears under a shirt cuff.
Criterion 1: Case Profile and Crystal
Two build styles dominate this reference. One uses a thin automatic so the mid case stays near the original height. The other uses an ETA 2824 clone, which is taller and usually forces a deeper case back.
Slim case, thin automatic
Pros
- Wears close to the genuine proportions and sits flat on the wrist
- Thin profile fits under a cuff, which matters for a 45 mm watch
- Miyota 9015 parts and service are easy to find in the US
Cons
- Date module is often a printed overlay, so alignment can drift
- Less material in the mid case, so dings show faster
- Rotor noise is noticeable on cheaper examples
Thicker case, ETA clone
Pros
- Movement is a proven design with wide parts availability
- Feels more substantial in hand, which some buyers prefer
- Better base for a genuine big date module
Cons
- Case back adds height the original does not have
- Sapphire to bezel gap is often wider than the reference
- Crown guards can look blocky on budget examples
Recommendation: if you wear the watch daily, take the thinner case. If you plan to have the date module serviced properly, the ETA clone platform gives your watchmaker more room to work.
Criterion 2: Dial, Date Apertures, and Bezel Insert
Check the date apertures first. The two windows should sit level with each other, on the same horizontal line, with matching border thickness. A common flaw is one window sitting a fraction high, which is visible the moment the dial catches light. Next, look at the applied indices: they should be set at the same height, with polished edges and a lume fill that does not spill onto the dial. On the bezel, the insert should be sapphire or ceramic with a lume pip that lines up with the 12 o'clock index when the bezel clicks into position.
Pros of a well finished dial
- Date reads cleanly at a glance instead of looking broken
- Lume color matches between dial and bezel pip
- Print weight on the dial text matches the reference photo
Cons to expect on cheaper builds
- Misaligned date windows that no adjustment will fix
- Green lume on the dial and blue lume on the pip
- Bezel insert with a printed rather than filled pip
Criterion 3: Movement and the Big Date Mechanism
There are two honest approaches here. One is a Miyota 9015 with a date wheel overlay that shows two numbers through the dial. The other is a true big date module mounted on top of the movement, with two independent discs and a jumping mechanism. Ask the seller which one you are buying. Overlay builds are cheaper and thinner. Module builds change date correctly at midnight instead of dragging through the change.
Pros of the overlay approach
- Lower cost and simpler service
- Keeps the case thin
- Fewer moving parts to fail
Cons of the overlay approach
- Numbers can sit at different heights
- Date change happens gradually, not at midnight
- Replacement overlays are hard to source later
Criterion 4: Water Resistance and Finishing
A dive watch replica lives or dies on its seals. Gaskets, crown threads, and case back sealing are the parts most often skipped. A build that has been pressure tested will carry a test result, even if the number is modest. A build sold as water resistant with no test is a dry land watch, and you should treat it that way. On finishing, look at the case flank brushing, the polish on the bezel edge, and the lug bevels. Sharp transitions read as cheap under indoor light.
Pros
- Tested builds handle rain, hand washing, and pools
- Screw down crown and case back seat with a clean turn
- Better resale if you decide to move it on
Cons
- Untested builds can fog or rust after one swim
- Pressure testing adds cost to the purchase
- Servicing seals later is a separate expense
Which Build Fits Which Buyer
If you want one watch for daily wear, choose the slim case with the thin automatic and accept the overlay date. It wears correctly and costs less to keep running. If you collect and rotate, choose the ETA clone platform with a real big date module, because the midnight date change and the correct thickness are things you notice every time you pick it up. If you swim or travel with your watches, spend the extra on a pressure tested example and a spare set of gaskets at purchase.
Inspection Checklist Before You Pay
- Photograph the watch head on with a ruler beside the case, then compare against your four reference numbers.
- Ask for a video of the date changing at midnight.
- Confirm both date apertures sit on the same line under a raking light.
- Check lume color match between dial and bezel pip in a dark room.
- Turn the bezel through a full rotation and listen for even clicks with no back play.
- Ask whether the case was pressure tested, and get the number in writing.
- Confirm the movement caliber and who will service it locally.
A fake Fifty Fathoms 5050 can be a satisfying watch when the case, the date, and the movement are chosen with intent. Get those three right and the small details stop being a gamble.