Buying Guide10 min read

How to Spot a Counterfeit or Doctored Coin

Counterfeits have gotten good — but most still fail basic physics. A scale, a caliper, and a few minutes of looking will catch the overwhelming majority before your money leaves your hands.

Bottom Line: The single best defense is to buy coins already graded by PCGS or NGC and to verify the certification number on the grader's site. Buying raw? Weigh it, measure it, and check the mintmark — fakes are usually off-weight, off-size, or wear an added mintmark.

Five quick tests

Test	What it catches	Tool
Weight	Wrong alloy or thickness — most fakes miss spec	0.01g scale
Diameter & thickness	Cast/struck copies that are off-size	Calipers
Magnet	Base-metal fakes (real US silver/gold/copper isn't magnetic)	Any magnet
Loupe the details	Casting seams, bubbles, mushy or tooled devices	10× loupe
Mintmark check	Added/altered mintmarks faking a key date	Loupe

All of this fits in our collector gear list — a scale, calipers, and a loupe are the cheapest insurance in the hobby.

The two scams to know

Added mintmarks

A common-date coin gets a tiny "D" or "S" soldered or glued on to impersonate a key (the classic 1916-D Mercury and 1909-S VDB fakes). Under a loupe, look for a mintmark that's mushy, wrong-shaped, tilted, or sitting on a disturbed surface. When in doubt, only buy the key dates graded.

Counterfeit slabs

Fake PCGS/NGC holders (often with a real-looking but fake coin inside) circulate, mostly from overseas sellers. Defeat them by typing the cert number into the grader's free verification — it must return the exact coin, grade, and matching photo. No match, or no photo, means walk away.

Where fakes hide

⚠️ Highest-risk situations:

Raw key dates and pre-1933 gold from new or overseas sellers.
Prices noticeably below comparable sales.
Bullion at "too cheap" premiums — counterfeit Silver/Gold Eagles exist.
Off-brand slabs dressed up to look like PCGS/NGC.

When the stakes are high — expensive keys, gold, or anything you can't verify — buy it already certified, or send a raw coin to PCGS/NGC yourself. The grading fee is cheap relative to the cost of a convincing fake.