A copied guitar body shape is a solved problem for any factory with a CNC machine, so shape alone authenticates nothing. The money in a genuine instrument sits in the places a copy cuts: tuner quality and branding, bridge and tailpiece metal and plating, pickup construction, the pots and wiring inside the control cavity, fret dressing, and finish work at the joints. Authentication that starts under the control cavity cover and at the fret ends catches copies that photograph beautifully, because a listing can hide a cavity and cannot hide the price logic that put a five dollar pot in a guitar pretending to be a two thousand dollar one.
Weight is a real clue here too. Substituted woods and hardware change it, and a model with a well documented genuine weight range that arrives far outside it has told you something no photograph could argue with.
Serial formats encode factory and date in most major brands systems, and a fake usually fails the logic rather than the existence check: a serial that decodes to a year the model was not made, a format from the wrong era for the features on the guitar, the same serial appearing across multiple listings, or a font and placement, stamped, inked, or on a decal, that does not match how that factory marked instruments in that period. Brand customer services will often verify a serial against their records for a prospective buyer, which is the strongest check available and costs one email. Use it before money moves on any high value listing, and treat a seller who refuses to provide the full serial as having answered the question.
The headstock is where copies spend their effort, and it still betrays them in the small geometry: logo script slightly wrong in weight or angle, inlay that is printed or flat where the genuine is cut material with depth, a truss rod cover with the wrong number of screws for the model and era, two screws where the genuine uses three is a famous tell in one major brand copies, and tuner bushings and string trees that do not match factory specification. None of these requires expertise to check once you know the genuine reference: the skill is comparison against a verified example, photograph by photograph, not a mystical feel for authenticity.
Neck construction closes the case on many models: scarf joints and heel shapes differ between the genuine factory method and the copy method, and they are visible in listing photos if a buyer knows to ask for the back of the headstock and neck, the two angles fake listings most often omit.
Demand the photographs fakes cannot survive: control cavity open, serial close up, back of headstock, fret ends along one side, and the guitar on a scale. Buy through a channel with buyer protection for authenticity, and for a genuinely valuable instrument pay for a local luthier inspection in the return window; an hour of bench time costs a fraction of a refinanced mistake. Calibrate confidence honestly: authentication of popular copied models is a mature skill with good reference material, and authentication of rare variants is genuinely hard, which is why provenance, receipts, case candy, and a verifiable chain of owners carry real value in that tier and their absence should discount the price, not just raise an eyebrow.
If this topic is useful, these earlier guides go deeper on connected questions: Counterfeit Perfume Listings: Authentication Clues Buyers Can Check, Counterfeit Headphones Listings: Clues in Sound, Serials, and Sellers, and Counterfeit Sunglasses: Listing Clues Beyond the Logo.
Decode the format against the brand published system to see if the factory and date it encodes match the model and its features, then ask the brand customer service to verify it, which many will do. A serial that exists but decodes to the wrong year or model is a stronger fake signal than a missing one.
Wrong or cheap hardware, low quality pots and wiring in the control cavity, poor fret dressing, logo and inlay that are printed or flat, incorrect truss rod cover screws for the model, weight far outside the genuine range, and a serial number whose logic does not fit the instrument.
Buying counterfeit goods for personal use is treated differently from selling them in most places, but reselling a copy as genuine is fraud, platforms prohibit the listings, and imports of counterfeit trademarked goods can be seized. The practical risk for a buyer is financial: the instrument is worth copy money, however much was paid for it.
Occasionally a distressed or mislisted genuine instrument appears, but a current, desirable model at a small fraction of its used market value, from a seller with thin history and stock photographs, is a counterfeit until proven otherwise. The verification steps cost little. Skipping them is what the price is counting on.