Service guidance
Coin authentication: how to tell if a coin is genuine
Before you insure, appraise, or sell a coin, it sometimes needs a more basic question answered first: is it real? Here's how authentication works and when it's worth doing.
What authentication actually checks
Authentication is a focused examination of whether a coin is what it claims to be — genuinely struck by the mint it's attributed to, in the metal it's supposed to be, without alterations like an added mint mark or a re-engraved date. It doesn't assess condition the way grading does; it answers a narrower, more fundamental question first.
Third-party authentication services examine weight, dimensions, metal composition, die characteristics, and surface details, then compare findings against known genuine examples. Coins that pass are often encapsulated in a tamper-evident holder along with any assigned grade.
Warning signs worth a closer look
- Weight or diameter that doesn't match the coin's known specifications
- A visible seam around the edge, which can indicate a cast rather than struck coin
- A mint mark that looks added on top of the surface rather than struck as part of the design
- Wear that looks artificially even or doesn't match the coin's high points
- A price well below what the coin's apparent date, mint mark, and condition would suggest
None of these confirm a fake by themselves — genuine coins can have unusual wear, and legitimate variations exist. They're reasons to get a second opinion, not conclusions on their own.
When authentication is worth the cost
It tends to make sense for higher-value pieces, coins purchased without a clear chain of ownership, anything you plan to insure or formally appraise, and pieces you have specific doubts about. For an ordinary circulated coin with modest value, the cost of authentication can easily exceed what's at stake.
Related reading
Related guidance
- Coin grading cost — what grading and authentication fees typically look like
- Coin collection appraisal — getting a formal value once authenticity is settled
- Sell a coin collection — why authentication often comes before a sale
Common questions
Coin authentication — common questions
How is authentication different from grading?
Authentication answers "is this genuine?" Grading assigns a standardized condition score once genuineness isn't in question. Many third-party services perform both together, but they are conceptually separate questions — a coin can be authenticated without being graded, though not the reverse.
What are common signs a coin might be counterfeit or altered?
Unusual weight or dimensions, seams or a slightly different color at the edge, "mint marks" that look added rather than struck, unnaturally uniform wear, or a price that seems too good for the apparent rarity. None of these confirm a fake on their own — they're reasons to have a piece looked at more closely.
Do I need every coin authenticated?
No. Authentication makes the most sense for higher-value coins, coins where you have specific doubts, or pieces you're about to buy, sell, or appraise formally. Routine circulated coins rarely need it.
What does authentication cost?
Fees vary by service and generally scale with a coin's declared value, similar to grading fees — see our grading cost guide for typical ranges. There are usually handling and shipping costs on top.
Can I authenticate a coin myself?
Basic checks — weight, dimensions, a magnet test for certain metals, and comparison against known genuine examples — can rule out obvious fakes, but they can't reliably confirm authenticity on their own. For anything of meaningful value, an independent third-party opinion is worth the cost.