Methodology

1. How we value cards

Every value is a comparable-sales estimate — built from actual recent sales of the same card at the same grade, never from a list price or an opinion. For each graded card we resolve its identity by its grading cert, then aggregate real closing prices across the major marketplaces — eBay, Heritage, Goldin, and PWCC — over roughly the trailing 90 days, weighted toward the most recent and most similar sales.

• Confidence reflects evidence. Cards with many recent comparable sales carry a higher-confidence value; thinly traded cards carry wider uncertainty, and we say so.
• Independent, redundant data. Market data comes from our pricing partner (CardHedge), with a second independent graded-comp source as an automatic fallback — so a single provider outage doesn’t leave a collection unpriced.
• Graceful degradation. If live data is briefly unavailable, we show the most recent known value, clearly labeled “as of” its date — rather than guessing.
• Nothing is fabricated. Cert numbers, population data, and sale prices are real or they’re left blank. We never invent a value or a cert to fill a gap.

2. The Slabline Score (0–1000)

The Slabline Score measures how well-protected a collection is — not how good the cards are. A pristine collection that’s uninsured and concentrated in one card can score lower than a modest, well-managed one. It’s a weighted blend of five factors, each scored 0–100:

• Insurance — 35%. Coverage relative to current market value, discounted by how stale the latest appraisal is.
• Concentration — 25%. Exposure to a single card: a larger top holding as a share of total value lowers the score.
• Storage — 20%. Self-reported protections — climate control, fire, theft, light — plus handling discipline.
• Liquidity — 10%. How readily holdings convert to cash at predictable prices, value-weighted across the collection.
• Provenance — 10%. Share of cards with a verified grading cert, plus documentation depth.

The five sub-scores combine on their weights into a 0–1000 composite, which maps to a letter band:

• A — 880+ · Excellent
• B — 750–879 · Strong
• C — 600–749 · Fair
• D — 400–599 · At Risk
• F — below 400 · Poor

Every score is stamped with a model version and recomputed whenever the collection, its inputs, or the market changes, so the number on screen always reflects current data.

3. Data sources & integrity

Card identity and population data come from the grading services (PSA · BGS · SGC · CGC · TAG) and their public records where available; valuations from the comparable-sales sources above. Insurance and storage details are self-reported by the collector — they drive the Insurance and Storage factors and are not independently verified by Slabline. We hold ourselves to a simple rule: real data or no data — we do not estimate a cert, a population, or a sale that didn’t happen.

4. Limitations

Values are estimates, not guarantees. Card markets are volatile and can move sharply; thinly traded cards are inherently less certain; and a comparable-sales estimate is not a substitute for a certified appraisal or an underwriter’s review. Confirm any value with a qualified appraiser and your insurer before relying on it for insurance, sale, or financial decisions. The Slabline Score is a directional risk indicator, not financial or insurance advice.