Authenticity cannot be settled on a video call, and for clothing the details that people check change with every production run, which is why this page asks rather than tells.
What to ask them to show
The main label and the care label, both close and in focus. The care label is inside a seam and is the one most often left unphotographed.
The inside seams and any lining, turned out where the garment allows.
Hardware close up — a zip run on camera, clasps worked.
Beading, embroidery or any applied work, close, and ask whether any of it is missing or loose. This is both an authenticity question and a condition question, and the condition half matters more often.
Measurements taken on camera, flat: bust across, waist across, length from the shoulder. For anything elasticated, relaxed and stretched.
What a refusal means
All of the above is quick for somebody holding the garment. A seller who will measure but will not photograph a label, or the reverse, has chosen which request to meet.
Notice reassurance arriving in place of a photograph. "It is completely original" answers a question you did not ask.
What this page will not do
It will not describe what any brand's labels, stitching or hardware should look like. The plan for this site flags this category as one needing somebody who follows it closely, and a confident list written from general knowledge would be worse than nothing — a buyer who has "checked the label" against something out of date has verified nothing.
For an expensive piece: photographs first, then somebody who buys that label often, then bid.
What protects you if you get it wrong
A counterfeit is not as described: returnable for 7 days whatever the store's policy says, and reportable.
Worth asking about packing, too — creasing, damp and beading that catches on everything in a parcel are the real-world risks here.
Questions people ask
What actually goes wrong most often?
Fit, by a long way. The measurements are the most valuable thing on this page.
Is a missing label a bad sign?
Not necessarily — labels get cut out because they itch. It does make the piece harder to evidence, so it should be priced as less certain.
Can I return something that does not fit?
That is up to the store. A faulty, damaged, wrong or misdescribed item is returnable for 7 days whatever their policy says; changing your mind is their decision.
More: spotting a counterfeit before you bid, Metzee's position on counterfeits, reporting a seller, questions to ask before bidding on womenswear.