Short answer
A replica Constellation 151.10.45.50.01.001 is a first copy built to mimic one specific Omega Constellation, the steel, black dial model that this reference number identifies. The number is a target, not a guarantee. Two sellers can both type 151.10.45.50.01.001 into a listing and ship watches that feel nothing alike, because the quality lives in the case, the bracelet, the dial printing and the movement, none of which the reference number describes.
So the useful question is not what the number means. It is which tier of build you are looking at, and whether the photos and specs prove it.
How the reference reads
Omega reference numbers come in six blocks, and each block carries information: family and case metal, then the bracelet or strap type, then the size code, then the movement, then the dial and the variant inside that run.
Treat that as orientation rather than gospel. Omega has changed its scheme more than once over the decades, and the size block does not always line up with the millimeter figure people expect. If a listing claims a case diameter, check it against the official spec sheet rather than trusting the number in the title.
What a first copy is trying to reproduce
The Constellation has a look you recognize from across a room. A star sits low on the dial under the Omega logo. Polished claws (the griffes) run down the case flanks at 3 and 9. The bezel is engraved with Roman numerals on many versions. The bracelet is a mono-rang design with buttress links and a taper that feels deliberate on the wrist.
Modern references in this family run a Master Chronometer automatic: chronometer rated, anti-magnetic to 15,000 gauss, certified through an eight-test protocol. A replica copies the silhouette and the dial furniture. It does not copy the certification.
What the better tiers get right
- Case profile. The claws sit flush and the lugs curve the way the genuine does.
- Dial work. Applied logo, star, and printed text hold up under a loupe instead of smearing.
- Crystal. Sapphire with a real anti-reflective coat, so the dial goes dark at an angle rather than milky.
- Bracelet fit. End links meet the case with no gap, and the clasp closes with a solid click.
- Weight. A steel case and steel bracelet should feel like steel, not like a hollow shell.
Where replicas of this reference fall short
- Thickness. Cases run a millimeter or two fat, which changes how the watch sits under a cuff.
- Bezel engraving. Roman numerals come out shallow and soft instead of crisp with polished edges.
- Star and logo placement. Small shifts are the first thing a Constellation owner notices.
- Date window. Font, position and magnification drift from the original.
- Crown feel. Winding grit and a crown that does not seat cleanly.
- Caseback detail. If the genuine has an exhibition back, movement finishing is the giveaway.
Checks to run before you pay
- Ask for photos of the actual unit, not catalog renders. Dated, on a plain background, front, back, clasp and lug sides.
- Get the measured case diameter and thickness in millimeters.
- Confirm the movement and whether the crown screws down.
- Ask about water resistance as a claim, not a fact. I treat any replica as splash safe until it has been pressure tested, and most never are.
- Read the return policy before checkout. No returns means no leverage.
Price bands you will see
Under about $150 you are in quartz territory with a stamped bracelet. The $200 to $400 range buys an automatic with a decent dial and a bracelet that mostly works. Above $400 the case shape, engraving and finish get closer, and the movement is where the extra money actually goes. Paying more than that for this reference is not buying accuracy, it is buying a story.
Living with it
Keep it out of pools unless you have had it tested. Do not take it to an Omega boutique or an authorized service center, because they will not touch it. A local watchmaker can swap a battery, regulate a movement or reseal a caseback. Resale value on any first copy is close to zero, so buy it to wear it. And a replica is not the genuine article: representing it as one when you sell it is fraud, in the US and most everywhere else.
Bottom line
The reference number tells you which Omega Constellation someone copied. It says nothing about the copy in front of you. Judge the tier, the photos, the measurements and the movement, and you will end up with a watch that looks right on the wrist instead of a listing that sounded right.