A "slab" is a tamper-evident plastic holder containing a coin certified by a third-party grading service: PCGS, NGC, ANACS, or ICG most commonly. The label on the slab identifies the coin and assigns it a Sheldon Scale grade (1 through 70). For high-value coins this grade is the single largest input into market price, so the integrity of the slab itself becomes the integrity of the entire transaction.
Counterfeit slabs are real and growing. They fall into two buckets: replica holders containing genuine coins (relatively benign; the coin is what it is, just regraded fraudulently), and replica holders containing counterfeit coins (the dangerous case, where the grading label is a lie about a coin that should never have been graded at all).
What we check at intake
Five passes, in order:
1. Weight against reference
Every common US coin has a US Mint specification: total weight in grams, alloy composition, fineness. A genuine 1881-S Morgan dollar weighs 26.73 grams ±2%. A typical Chinese counterfeit weighs 5 to 10 percent less because the metal is wrong (usually lead with a silver wash, sometimes pure copper or zinc).
USCNE's intake form has a measured-weight field that auto-compares against the reference. A red badge means the coin is outside Mint tolerance; the operator is required to investigate before the item can be listed. This single check catches most counterfeits regardless of how convincing the slab looks.
2. Slab label typography
Genuine slabs from major services have consistent fonts, kerning, and color reproduction. Counterfeit slabs often have small typography errors visible under 10x magnification: misaligned text, wrong font weight, registration drift on the colored bands. Reference photos from the grading services are publicly available and worth pulling up side-by-side during intake.
3. Hologram and security features
PCGS uses a hologram on the back of every slab that shifts color when tilted. NGC uses a foil-stamped element. Counterfeit slabs sometimes copy these features but rarely well; a quick tilt test catches most fakes. New holders introduced after 2020 add additional security layers that older counterfeits do not replicate.
4. Cert number lookup
Every certified coin has a unique cert number printed on the label. The grading services maintain free public lookup tools that return the coin's date, mint mark, denomination, and grade. If the lookup data does not match the label or the coin in the slab, the slab is counterfeit or has been tampered with.
USCNE will be wiring this into intake automatically (PCGS CoinFacts API + NGC Verify) so the lookup happens with one click. Until then, operators do it manually for any coin valued above $200.
5. Cert collision detection
This one is unique to USCNE's roadmap. The same cert number cannot legitimately appear on two coins simultaneously. We are building a check that compares cert numbers against active listings on eBay, Heritage, and GreatCollections; a hit means at least one of the coins is a counterfeit slab using a copied number. Critical collisions will hard-block the listing.
What this means for buyers
Every certified coin in a USCNE auction has been weighed, label-inspected, hologram-checked, and cert-verified. The 7-day inspection window plus authenticity guarantee on certified items means a buyer can return any coin that fails independent third-party authentication, with the platform absorbing return shipping and the original transaction price. The combination is meant to make a USCNE certified coin as safe to buy as one bought directly from a major dealer at retail.