Sports cards use the same grading machinery as any trading card, with one extra variable that decides more of the price than the grade does.
What is assessed
Centring, corners, edges, surface. Four areas, every time, at every service.
The scales
1 to 10, with one major service grading in half-point steps and publishing sub-grades for each area. Numbers are not interchangeable between services — say which one.
The parallel comes first
Before any grade matters, establish which version of the card it is. The same photograph can exist as a base card and a dozen parallels at very different scarcities, and a 9 of a common parallel is worth less than a 7 of a scarce one.
A grade without a parallel is half the information. What cards are worth.
Trimming
Modern cards are made to a standard size, so a trimmed card measures short. Services check for it, and a trimmed card that reaches a slab has usually been caught. For raw cards, measuring on camera is a strong, cheap thing for a seller to do.
When grading is worth it
When the gain beats the fee and the wait. For most cards it does not — and submitting a 7 hoping for a 9 is a gamble with a cost attached either way.
Describing a raw card honestly
Say what you examined and under what light, and give the four areas in words. Never put a hoped-for number in a title: written as a number it is read as a fact. Common mistakes.
Questions people ask
What is a sub-grade?
A separate score for each of the four areas, published by some services alongside the overall grade.
Do Indian cricket cards get graded?
The services grade cards generally. Ask the seller which service and read the label.
Does a low grade still sell?
Yes, of a card people want. Low grades of sought-after cards have a real market.
More: describing cards, buying them.