How we source card facts
Where the values and guides on Grailday come from, and what we do when we get something wrong.
Who writes our guides
The Grailday team writes and edits every guide. We use AI tools to help research and draft; an editor then reads the whole draft, checks each fact, figure and date against its source, and signs off before it is published.
Until our editors' profiles are up, guides are signed by the team: Grailday Editors.
What we cover
The questions collectors ask: grading, card values, sets and products, players and characters, and how packs of graded cards work. Each guide answers its question in the first two sentences and dates any table of prices or values.
Where the facts come from
We rely on primary sources: the grading companies' own pages, publishers' official announcements, league sites and the published results of auction houses. Each figure is traced to its source and dated before a guide is published, and we don't pass along one we can't trace. A guide does not link out.
How we show values
Every figure on a card page says what it is and carries a month. Value is checked against recent sales of that exact grade. Estimated value is our own guide, used when there are too few recent sales to check it. Last sold is a sale that ran below our usual figure, so we show the sale. When there are not enough recent sales to price a card, we show no number. None of these is an offer to buy or sell. A card page shows a price only when the card is on our Market, and that price is the seller's. Past prices are dated facts, not predictions.
Our guides never predict where a card's value is headed, and nothing on Grailday is financial advice.
Grailday is a marketplace
Grailday is a marketplace for real cards: cards you browse in the Market, and packs you open. Guides and card values help you find your grail, and link to the Market and our packs where they fit. That never decides the facts: guides cover the whole hobby, name other companies where they matter, and keep the same sourcing rules when we compare ourselves with anyone else.
Corrections
If we get something wrong, we fix it and add a dated note at the end of the guide that says what changed. To report a mistake, use our contact form; please include the page and what you think is wrong.