Quick answer

A "fake IW376067" is a watch wearing IWC's Aquatimer chronograph reference number that did not come out of Schaffhausen. That phrase covers two very different products. A replica is sold openly as a copy. A counterfeit is sold as the real thing, usually with a box, a card, and a story about an uncle who bought it duty free.

The steel can be the same between those two. What differs is the claim, and the claim is where the money and the legal trouble sit.

Why this reference attracts copies

The Aquatimer chronograph is a big, legible, toolish dive watch with an internal rotating bezel and a busy dial that hides small errors well. It also sits inside a crowded block of reference numbers, so a buyer searching one number lands on listings for half a dozen neighbours. Dishonest sellers lean on that confusion. Some listings show photos of a genuine watch and ship something else. Others just swap the number in the title and hope nobody checks.

The checks that actually decide it

• Caseback engraving. Reference and serial should be cut into the metal with clean edges and consistent depth. On most copies the digits are shallow, the spacing is too even, or the number sits on a sticker, a thin plate, or an aftermarket caseback.
• Movement. Aquatimer chronographs have used both modified Valjoux-based calibres and IWC in-house movements depending on the generation. Ask for a photo of the movement and of the open caseback. A seller who avoids that request is telling you something.
• Crown and pushers. The screw-down crown should thread smoothly and seat flush against the case. Pushers on a copy often feel gritty, sit too proud, or have a long, spongy throw.
• Bezel and crystal. The internal bezel should turn with light, even resistance and the minute track should line up cleanly at twelve. Crystal coating is the tell most people miss: genuine anti-reflective coating kills reflection at an angle, while cheap coating leaves a blue or purple sheen.
• Dial and lume. Look at the printing under magnification. Applied indices should sit level and reflect light the same way across the dial. Lume that glows unevenly, or a date wheel with the wrong font, is a strong signal.
• Weight and bracelet fit. Solid end links should sit flush against the case with no gap or rattle. A bracelet that pinches hair or flexes at the lugs usually means thinner links and lighter steel.

Genuine, replica, counterfeit

These are three separate transactions, and mixing them up is how people get burned.

• A genuine watch comes with IWC service history, a matching serial across case and paperwork, and a price that reflects it.
• A replica is a copy sold as a copy. You know what you are buying, you pay accordingly, and no one claims otherwise.
• A counterfeit is a copy sold as genuine. This is the one that costs real money and carries legal exposure in most countries.

Red flags in a listing

• Photos borrowed from a dealer or a review site, with no shot of the actual caseback.
• A serial number that does not match the one printed on the card.
• Paperwork with a soft, generic font or a seller name that does not exist.
• A price far below the going rate for that reference, explained by "moving it fast" or "no box."
• Pressure to pay outside a platform with buyer protection.

Deciding what you want

If your goal is a genuine IW376067, walk away from anything you cannot inspect or have inspected, and pay for a service quote from a watchmaker before money changes hands. If your goal is the look of an Aquatimer chronograph at a fraction of the cost, buy from a seller who says plainly that it is a replica, shows the movement, and stands behind the specs. The one thing worth avoiding is the middle ground: a copy priced like the real thing.