Founded in Florence in 1921, Gucci uses one of the most consistent interior marks in luxury: a leather tag stamped with the brand and a serial number. That consistency makes it a useful place to start, and also an easy thing to copy.
The leather tag and serial number
Inside most modern Gucci bags, a rectangular leather tag is stitched to the lining, usually on the back wall. The front is heat-stamped with ®, then "GUCCI" and then "made in Italy". 1stDibs's guide stresses that the lettering should be centred, correctly spelled and in the house's typeface. The reverse carries a serial number of 10 to 13 digits, generally in two rows: the first is the style number and the second the supplier code. A tag stitched to the lining on all four sides cannot be turned over, which is a red flag in itself. Serial numbers are not unique to one bag, and they are copied, but searching the style number is useful: if it returns a wallet and you are looking at a hobo, something is wrong.
The controllato card
New Gucci bags come with a small grey "controllato" (checked) card showing the Gucci name, the word controllato in lowercase and a row of numbers. It is generic, often lost and easily copied, so its absence on a pre-owned bag means little and its presence means less.
The Gucci Authenticity Tag
On selected bags, silks and travel pieces, Gucci now embeds an NFC Authenticity Tag. Gucci explains that owners scan it with the Gucci app on an NFC-enabled phone; on the Jackie, for example, it sits about halfway up the back of the bag. The tag is available only on selected items and cannot be added later, so most older pieces will not have one.
Canvas, stitching and hardware
GG Supreme canvas should be even in colour, with the interlocking G's crisp and the pattern running straight. Stitching should be small, tight and regular inside and out. Horsebit, Jackie and bamboo hardware should be solid and smoothly finished; bamboo is real cane, heat-bent, so the nodes are slightly irregular rather than moulded. Stamping on hardware should be clean and the logo the correct shape.
Packaging
Dust bags, boxes and cards are copied in volume. Use them only as background.
When to get a professional opinion
For vintage Gucci, where tags and stamps varied, and for any high-value bag, use a reputable reseller or authentication service. The RealReal combines staff inspection with Entrupy scanning; Fashionphile and Rebag authenticate in house.