Grades, Slabs, and “Details”

What NGC and PCGS labels mean on wreck coins, what a details grade does and doesn’t say, and what certification is measurably worth.

On a wreck coin, a slab is doing three jobs: authenticating the coin, describing its surfaces, and — sometimes — repeating a provenance claim on the label. Most sea-salvaged coins are not assigned a numeric grade at all; they come back “Genuine” with a descriptor such as Shipwreck Effect, and the market pays for that certainty. In our August 2026 eBay study, slabbing carried a measurable premium: El Cazador 2 reales cleared a $200 median in holders against $75 raw.

What does the Sheldon 1–70 scale actually measure?

The numeric scale runs from Poor-1 to Mint State-70 and measures wear and preservation on a coin that circulated normally on land. AU-50 through MS-63 is where most collector-grade material sits; anything above MS-65 is a condition rarity in colonial series.

That scale assumes a coin whose surfaces were shaped by handling. A coin whose surfaces were shaped by seawater does not fit it, which is why wreck coins usually leave the numbers behind.

Why do most wreck coins get “Genuine” instead of a number?

Immersion etches fields, forms crystalline deposits and softens high points in a pattern unrelated to circulation. Graders therefore authenticate the coin and describe the surface rather than assign a wear number. NGC's Shipwreck Effect designation is the common wreck outcome; PCGS uses a Genuine holder with a details descriptor.

This is not a downgrade in disguise. For salvaged material it is the accurate label, and buyers treat it as such — a named-wreck Genuine holder frequently outsells a numerically graded example of the same undocumented type.

• Genuine · Shipwreck Effect — Authentic coin, surfaces consistent with long immersion — Not a claim about which wreck, unless the wreck is named
• Genuine · [Wreck name] — Grader accepted documentation tying the coin to that salvage — Not a numeric condition grade
• Genuine · Details (cleaned, environmental damage, tooled) — Authentic, with a stated problem that caps value — Not fake — and not necessarily a bad buy at the right price
• AU-53, MS-62, etc. — Numeric grade — surfaces judged by circulation wear — Rare on sea-salvaged coins; more common on land finds and milled issues

What does a “details” grade tell you?

A details grade means the coin is genuine but carries a condition problem the grader will name: cleaned, tooled, environmental damage, holed, repaired. The coin is still collectable; it is simply priced against its problem instead of its type.

Two of those words matter more than the rest. “Cleaned” means someone worked the surfaces after recovery, which usually costs more value than the dirt would have. “Tooled” means metal was moved — and on a cob, tooling is most often found on exactly the two features that set the price, the date and the assayer initial.

A details coin is honest goods at a discount. What you should never pay is a problem-free price for a details holder.

What is certification measurably worth?

We measure this rather than assert it. Across 569 sold eBay listings in August 2026 totalling $212,301, the same coin type sold at consistently different levels raw and slabbed.

• El Cazador 2 reales — $75 — $200 — ≈2.7x
• El Cazador 8 reales — $187 — $288 — ≈1.5x

Should you slab a raw coin you already own?

• Worth considering when the coin is a common type with a wide raw-to-slabbed spread and clean surfaces.
• Usually not worth it when total fees approach a meaningful share of the coin's raw value.
• Rarely worth it on a coin that will come back with a details grade — you pay to publish the problem.
• Always worth it when the salvage documentation would let the grader name the wreck on the label, because the label travels with the coin forever.

How do you verify a holder is what it says?

• Look up the certificate number on NGC's or PCGS's own verification page and compare their images to the coin in front of you.
• Check that the holder is intact and unaltered — reholdered or cracked-and-reinserted coins lose the chain.
• Read the wreck name on the label literally. If it is absent, the seller's wreck claim is unsupported by the grader.
• Match the weight and denomination on the label to the coin.

Frequently asked questions

• Why does my shipwreck coin have no number grade? Because seawater alters surfaces in a way the circulation-wear scale cannot describe. Graders authenticate the coin and describe the surface instead — usually as Genuine with a Shipwreck Effect or similar designation.
• Is a “details” coin a bad coin? No. It is a genuine coin with a named problem such as cleaning, tooling or environmental damage. It should simply be priced against that problem rather than at problem-free levels.
• Does slabbing increase what a wreck coin sells for? In our August 2026 eBay data it did, by type: El Cazador 2 reales cleared roughly $200 slabbed against $75 raw, and 8 reales roughly $288 against $187. Premiums vary by type and are not guaranteed.
• Does the slab prove which wreck the coin came from? Only if the wreck is named on the label. A Shipwreck Effect designation alone confirms marine surfaces, not a specific salvage source.

Sources

• NGC — Shipwreck coin certification and “Genuine / Shipwreck Effect” designations — https://www.ngccoin.com
• PCGS — Grading standards and “Genuine / Details” grade definitions — https://www.pcgs.com
• Dark Tide Relics, Market Report No. 19 — The eBay Ledger (569 sold listings, August 2026; captured August 27, 2026)
• Dark Tide Relics, Market Report No. 17 — The August Ledger (529 Heritage Auctions lots, $895,237 realized, August 2026)