Buying coins, stamps, or currency from a dealer is an investment decision—whether you're spending $50 on a vintage postage set or $5,000 on rare numismatic pieces. Without the right documentation, you're exposed to authentication fraud, misrepresented grades, and zero recourse if something goes wrong.
Certificate of Authenticity (CoA)
A Certificate of Authenticity is non-negotiable for high-value purchases, especially coins and currency above $200. This document should include the dealer's name, contact information, item description (denomination, year, mint mark, condition), and their signature or seal. For graded coins, the CoA references the professional grading service (PCGS, NGC, or similar) and the assigned grade—say, "1980-S Kennedy Half Dollar, MS-67."
Request that the CoA describe why they've authenticated the piece. Generic certificates mean nothing; legitimate dealers explain identifying features or reference their authentication methodology. If a dealer refuses a CoA or offers a vague one, walk away.
Detailed Receipt or Invoice
Your receipt should itemize everything you're purchasing with specific, verifiable details. Instead of "vintage coin lot," insist on line-by-line entries: "1945 Canadian Silver Dollar, XF Grade, $180" or "50 Mixed Worldwide Stamps, 1950-1970s, $45." Include the date of purchase, total amount paid, and the dealer's business name and license number.
Many dealers price coins at $15–$500 depending on rarity and condition; stamps often range $10–$300 per lot depending on era and origin. Your invoice should reflect these realistic prices and break them down item-by-item. This protects you if a dispute arises and helps with insurance claims.
Grade or Condition Report
For numismatic and philatelic collections, condition is everything. Professional grading services assign standardized grades (Poor, Fair, Good, Very Good, Fine, Very Fine, Extremely Fine, About Uncirculated, Mint State). A coin marked "MS-65" is fundamentally different in value from "VF-20"—the first might be worth $500, the second $50.
Ask your dealer for a condition report that matches the grading scale. For stamps, this means noting cancellations, hinge remnants, centring, and perforations. Currency dealers should describe tears, stains, foxing, or ink loss. If they won't commit to a specific grade in writing, that's a red flag.
Provenance Documentation
Provenance—the item's ownership history—builds confidence, especially for rare or historically significant pieces. High-end dealers maintain records showing where they acquired a piece. For coins over $1,000 or rare currency, ask for acquisition documentation or a brief provenance statement.
This doesn't need to be elaborate; it might simply state "acquired from estate liquidation, March 2022" or "sourced from private collection, verified authentic." It shows the dealer tracks their inventory responsibly and aren't offloading stolen goods.
Insurance Valuation and Appraisals
If you're spending significantly—$500 or more on a single piece or collection—request a professional appraisal from an independent numismatist or philatelist. This is separate from the dealer's CoA. An appraisal establishes fair market value for insurance purposes and provides third-party authentication.
Appraisals typically cost $75–$200 depending on collection size and complexity but are worth it for valuable holdings. Your homeowner's or renter's insurance won't cover collectibles without proper documentation and appraisal value.
Storage and Handling Guidelines
Quality dealers provide care instructions: how to store coins (acid-free holders, climate-controlled spaces), stamps (mylar sleeves, avoid direct sunlight), and currency (protective sleeves, humidity control). Request these guidelines in writing or ask them to email them to you.
Checking Dealer Credentials
Before any purchase, verify the dealer's standing. Look for membership in the American Numismatic Association (ANA), Professional Numismatists Guild (PNG), or the American Philatelic Society (APS). Mercoly helps you compare and find trusted Coins, Stamps & Currency providers in one place, making credential verification easier.
Frequently Asked Questions
Q: Do I need a Certificate of Authenticity for every purchase? CoAs are essential for coins and currency over $200 or any stamp lot claiming rarity; smaller purchases from established dealers may not require them, but it's always safer to ask.
Q: What if a dealer refuses to provide detailed documentation? Decline the transaction—legitimate dealers have nothing to hide and routinely provide receipts, grades, and authentication documents.
Q: How do I know if a condition grade is accurate? Cross-check the dealer's grade against independent grading service standards (PCGS.com, NGC.com) and request references or past sales comps at that same grade level.
Start building your collection with confidence by always requesting complete documentation upfront.