Authenticity cannot be settled on a video call. In this category there are two separate worries — a reprint sold as original, and a real card trimmed to look better — and both are argued from photographs you can ask for in the moment.
What to ask them to do on camera
Hold it square on, filling the frame, both faces. Square on matters: an angled photograph hides the edges, and the edges are where both of this category's problems show.
Show the four corners and all four edges, close.
Tilt it slowly under one light so you see the surface rather than a reflection.
Take it out of a plain sleeve if it is not graded, or say plainly that they would rather not.
For a graded card: the label, the case front and back, and the case edges.
What a refusal means
A seller holding a card during a live show can do all of this in under a minute. Declining the square-on shots while offering more angled ones is the thing to notice.
"It is raw but it would grade well" is an opinion about a future event, and it should not change your price.
What this page will not do
It will not tell you what a correct card measures, how a genuine surface prints, or how to recognise a trim. The measurement especially: a buyer who has "checked the size" against a number they read somewhere has verified nothing and now believes they have, which is worse than knowing they are guessing.
Take the photographs to somebody who grades, or buy a graded card.
What protects you if you get it wrong
A reprint sold as original, or a trimmed card sold as untouched, is not as described: returnable for 7 days whatever the store's policy says, and reportable.
Questions people ask
Is a graded card safe?
Safer. The question moves to the holder, and holders are faked, so ask for the case edges and the label.
Why does square on matter so much?
Because the edges and the borders are the evidence, and an angle hides them. It is the cheapest request you can make.
Should I ask for the card to be measured?
You can ask for a photograph with a ruler alongside. Just do not treat your own reading of it as a verdict.
More: spotting a counterfeit before you bid, Metzee's position on counterfeits, reporting a seller, questions to ask before bidding on sports cards.