Card Grading Standards
How PSA, BGS, and AgentGrail AI evaluate a card — the four criteria, the centering tolerance table, and exactly what each letter grade means.
The Four Grading Criteria
PSA, BGS, and SGC all evaluate the same four attributes, though they weight them slightly differently and use proprietary scales. AgentGrail follows the PSA weighting published on their official grading standards page.
The distance between the printed image and each card edge. PSA measures left/right and top/bottom independently. A 60/40 split is the accepted PSA 10 floor — anything tighter on the minor axis risks a grade deduction.
The sharpness of all four corners under 5× magnification. Wear shows as fraying, rounding, or white specs (chipping). Corners carry the highest weight because they're the most visually obvious defect and the hardest to hide.
The four straight edges of the card. Nicks, chips, or roughness along the cut line signal wear. Edge defects often come from poor storage — even a sleeve can nick an edge over years.
Scratches, print lines, stains, and gloss consistency on both faces. Head-on phone photos rarely capture surface defects — raking light at an angle is required. AgentGrail marks surface N/A on standard photos and recommends professional submission for PSA 10 candidates.
Weights are PSA published standards. Surface is scored separately but excluded from AgentGrail's automated sub-criteria gate — head-on phone photos cannot reliably measure surface gloss or print defects without raking light.
Grade Scale — A through E
AgentGrail maps PSA's 10-point scale to five letter bands. The letter badge you see on every card comes from the most conservative signal across three inputs: the AI classifier grade tier, the centering measurement, and the per-criterion sub-scores.
| Letter | PSA Equivalent | Max centering | What it means |
|---|---|---|---|
| A | PSA 10 — Gem Mint | 60/40 | Perfect or near-perfect. Virtually no wear visible at 5× magnification. |
| B | PSA 9 — Mint | 65/35 | One minor defect allowed — slight corner wear or minor print dot. Still investment-grade. |
| C | PSA 8 — Near Mint–Mint | 70/30 | Very light corner wear or a minor surface imperfection. Solid collectible. |
| D | PSA 7 — Near Mint | 75/25 | Slight rounding on one or more corners. Still presentable and well-centered. |
| E | PSA 6 or below | 80/20+ | Visible defects on multiple criteria. Typically not worth grading fees unless the card itself is rare. |
Centering Tolerance Table
AgentGrail's centering gate converts border pixel measurements to a 0–100 score, then maps that score to the worst grade the card can earn — even if the AI classifier predicted a higher grade. Scores below 40 are treated as measurement noise (refractors, one-touch holders, angled shots) and capped to no-grade.
| L/R or T/B ratio | Centering score | Grade cap |
|---|---|---|
| 55/45 or better | ≥ 90 | PSA 10 safe zone |
| 60/40 | 80 | PSA 10 floor (SCRUM-4130) |
| 65/35 | 70 | PSA 9 floor |
| 70/30 | 60 | PSA 8 floor |
| 75/25 | 50 | PSA 7 territory |
| Worse than 75/25 | < 50 | PSA 6 or below |
Centering thresholds follow PSA's published standards. The 60/40 floor for PSA 10 was aligned in SCRUM-4130 (2026-06-17) after cross-referencing the official PSA grading page. Prior versions used a 55/45 floor that was too strict.
How AgentGrail AI Scores a Card
- 1Photo quality gate — AgentGrail first checks if the photo is usable — blur, glare, sideways cards, and busy backgrounds trigger a coaching prompt rather than a grade. A bad photo → bad grade is a false negative we actively try to avoid.
- 2CLIP image embedding — The card photo is encoded into a 512-dimensional visual vector by a CLIP ViT-B/32 model trained on hundreds of millions of images. This captures overall visual condition beyond what rule-based scoring can see.
- 3Per-criterion sub-scores — OpenCV measures centering border widths and corner/edge sharpness, producing 0–10 scores for each. On low-resolution images (< 1,000px shortest side, typical of eBay thumbnails) these scores are too noisy to trust and are dropped from the cap — only the CLIP verdict stands.
- 4Grail head verdict — A gradient-boosted classifier combines the CLIP vector with the per-criterion sub-scores into a single BUY / PASS / REVIEW probability. This head is trained on thousands of labeled cards across sports and eras.
- 5Conservative reconciliation — The final letter badge is the most conservative of: the grail head tier, the centering gate, and the sub-criteria weak-link cap. If any signal says the card is a C, the badge shows C — even if the others said A.
Grader Comparison
PSA, BGS, and SGC use the same four criteria but differ in subjectivity and labeling.
| Grader | Top grade | Sub-scores shown? | Notes |
|---|---|---|---|
| PSA | PSA 10 Gem Mint | No | Most liquid market. Highest premium per PSA 10. Population report available via PSA API. |
| BGS | BGS 10 Pristine / Black Label | Yes — on label | Shows centering/corners/edges/surface separately. BGS 9.5 ≈ PSA 10 in many markets. Stricter surface standards. |
| SGC | SGC 10 Pristine | No | Fast turnaround, popular for vintage. SGC 10 trades at a discount to PSA 10 for modern cards. |
| AgentGrail | A (PSA 10 candidate) | Yes — in drawer | Prediction only — not an official grade. Calibrated to PSA outcomes on a labeled training set. |
Not investment advice
AgentGrail AI provides condition estimates to help collectors make informed decisions. We are not a grading company and our AI predictions are not official grades. Always verify with a professional grader before making significant purchases. Past model performance does not guarantee future accuracy.
PSA® is a registered trademark of Collectors Universe, Inc. Beckett Grading Services (BGS®) and SGC® are independent companies. AgentGrail has no affiliation with any grading company.