Short answer
The Ladybird is a genuine Longines collection, a small ladies' watch line that goes back to 1957 and is still sold today. The "2138" part is the problem. Longines stamps its case backs with references that start with the letter L, followed by digits and dots, in the shape of L4.xxx.x. A bare four digit number is not a Longines reference. It is usually a seller code, a stock number, or a stamp from a third party case. When a listing leans on "2138" and never shows an L number, that tells you the seller either does not know the watch or does not want you to check it.
What the number 2138 usually is
On the listings I have gone through, a plain four digit number shows up in three places: a dealer's internal inventory code, a case back stamp on an aftermarket or replacement case, and once in a while a movement serial pulled from a service note. None of those is a Longines reference. So if someone advertises a "Ladybird 2138," ask them to send a photo of the case back with the full L number readable. If they stall, that is your answer.
What a real Ladybird looks like
- Size. The Ladybird is built around a very small movement, so the case is typically 20 to 26 mm across. Copies often come in at 30 mm or more, and the proportions go wrong on the wrist.
- Reference. An L number on the case back that matches the number on the card or hang tag.
- Dial. Fine printed text, a clean winged hourglass logo, and hands sitting level with the dial. On fakes the print looks heavy and the wings of the logo melt together.
- Case back. Deep, crisp engraving with sharp edges. Counterfeit cases are cut shallow, and the letters blur under a loupe.
- Crown. Signed, the right size for the case, and it sets with a firm click instead of a soft grind.
The checks I run before money changes hands
- Ask for a straight on photo of the case back with the reference readable.
- Look that exact reference up. You should find the same case size, dial layout, and movement family.
- Compare the dial font to catalog photos of that reference, not to another listing on the same site.
- Check the bracelet or strap. Original hardware carries markings, and the end links meet the case with no gap.
- Ask what movement is inside and whether the watch has ever been serviced. A vague reply is a reply.
Movement and paperwork
Modern Ladybird pieces run on Longines signed quartz calibres, and older ones are mechanical with an L prefixed calibre number. Either way, the movement should be marked and should match what the reference calls for. Papers matter here. A box alone proves nothing, but a warranty card with a matching reference and serial, plus a service record, is hard to fake cheaply. Missing papers on a two thousand dollar ladies' watch knocks real money off the price, so use that as leverage or walk.
Bottom line
A Ladybird is a real watch. A "Ladybird 2138" is a listing, not a model. Judge the piece on the L reference, the case size, the engraving, and the dial print, and buy from someone who will answer questions in writing. A replica or a franken build will not take genuine parts, will not service cleanly, and will not hold value, which is fine if you know that going in and not fine if you paid real money for it.