Ask before the show if you can — questions on a listing are public, so the answer is there for everyone who comes after you.
And ask early in the lot. On a sudden-death item the clock does not move for a question.
The questions
"Can you weigh it on camera?" For plain gold and silver, weight and purity are most of the price. Non-answer: "It's about twenty grams." Good answer: the scale, with the figure settling.
"Can you show the hallmark, and what is the HUID?" A hallmarked piece carries the BIS mark, the purity in karat and fineness, and a six-character HUID. With the number you can check it yourself. Buying jewellery.
"Is anything missing or replaced?" A missing stone is the single most commonly hidden fault here. Ask for the setting shown.
"Has the stone been tested, and by whom?" A report is worth its laboratory's name. No report means untested, and untested should be priced as untested.
For a watch: "Can you show it running, and what is original?" The second hand moving, for long enough to be convincing. Then dial, hands, crystal, crown and strap — what is original and what has been replaced.
What a hallmark does not do
It does not travel from the video to the parcel, and nobody assays anything over a call. That is not a reason to avoid the category; it is a reason to weigh the price against what was actually shown.
What protection covers
A weight well below what was shown, an unhallmarked piece sold as hallmarked, a watch sold as running that does not: seven days from delivery.
Questions people ask
Can Metzee check purity for me?
Should I bid on unhallmarked gold?
At unhallmarked prices, from a seller who says so plainly.
What if the HUID is not given?
Ask once. If it is not forthcoming, treat the piece as unverified.
More: what it is worth, common mistakes.