Sunglasses serial number checker, read from the arm

Not in the sense of a number unique to your pair. The code inside the arm is the frame code: the model, the color and the size. Every pair of the same model and color carries the same one. A few brands engrave something extra, such as the number on older Cartier frames or a code etched into some Prada lenses, but no public source explains what those encode.

Inside the arms. One arm carries the frame code, usually the left, and the other carries the brand name, where it was made and the CE mark. Kering Eyewear, which makes Gucci, Saint Laurent and Cartier eyewear, says its style code can be on either arm. On thin metal arms the print is small, so a magnifier or a phone photo helps.

Three of them are sizes in millimeters. The first is the lens width, the second, after the small box, is the bridge between the lenses, and the third is the temple length. The rest is the model number and the color code, and many arms end with the lens category, such as 3N.

The number is the lens filter category from 0 to 4, set by the ISO 12312-1 standard. Category 3, the usual sunglass tint, lets through 8 to 18 percent of light, and category 4 is too dark for driving. On Luxottica-made frames such as Ray-Ban and Prada, N after it means the lens is not polarized and P means polarized.

Prada offers no public lookup. What you can check is the arm code: S or V, PR and the model, the size, then the frame and lens color codes, such as SPR 17W 49□20 1AB-5S0 145 3N. Shops write the same frame as PR 17WS 1AB5S0. Prada's own store lists its frames under the same model and color codes, so you can compare the color it names with your pair.

Not from Cartier. Cartier eyewear made by Kering Eyewear, since 2017, carries a style code such as CT0002S with a colorway number, and this checker reads it. Older frames made by Cartier itself carry the Cartier signature and an engraved number instead. No public source says what that number encodes, and Cartier offers no public lookup for either, so a boutique is the place to ask.

Read the code inside the left arm, such as SMU 09W 53□22 1AB-5S0 135 3N. S means sunglasses, MU and 09W are the model, then the lens width and bridge, the frame color 1AB and the lens color 5S0, the temple length and the lens category. Miu Miu's own store lists its frames under the same model and color codes, so you can compare them with your pair.

Inside the left arm, a Versace frame reads MOD. and four digits, such as MOD. 4361 GB1/87 53□18 140 3N. The four digits are the model, sold in shops as VE4361. GB1 before the slash is the frame color and 87 after it is the lens. The other arm carries VERSACE and MADE IN ITALY.

Kering Eyewear has a public page that returns the declaration of conformity for a Gucci, Saint Laurent or Cartier style code. Finding it confirms the model exists. It cannot say whether a pair is genuine, because a counterfeit can carry a real style code.

Not on that alone. Ray-Ban makes frames in Italy and in China, and retailers that sell genuine stock say so. The country on the arm should match the box and the paperwork, and the code should name the model you are holding.

No. The CE mark is the maker's own declaration that the sunglasses meet EU safety rules, and counterfeiters print it too. It tells you nothing about who made the pair.

Several brands print one form inside the arm and use another in shops. Prada's SPR 17W is PR 17WS in listings, Versace's MOD. 4361 is VE4361, Burberry's B 4216 is BE4216, and Tom Ford's TF711 is FT0711 on its own store. The checker reads both forms.