Guides · Coins
Coins
How to size up coins at auction: what to check, key dates and mint marks, red flags, and free certificate and price lookups.
What to check
- Date and mint mark (look below or beside the date, or on the reverse, depending on the series).
- Wear on the high points; cleaning (unnatural shine, fine hairline scratches) cuts value sharply.
- For graded coins, the holder brand and the certificate number; verify the number online before you bid.
- Metal content: many United States dimes, quarters and halves dated 1964 or earlier are 90% silver.
Key marks and dates
- Pre-1965 United States dimes, quarters and halves: 90% silver.
- 1965–1970 Kennedy halves: 40% silver.
- 1942–1945 "war" nickels with a large mint mark over Monticello: 35% silver.
- Morgan dollars (1878–1904, 1921) and Peace dollars (1921–1935): 90% silver.
- Mint marks to know: CC (Carson City), S (San Francisco), D (Denver), O (New Orleans); no mark usually means Philadelphia.
⚑ Red flags
- Raw coins described as "uncirculated" or "rare" with no photos of both sides.
- Holders from unfamiliar grading companies; stick to Professional Coin Grading Service (PCGS), Numismatic Guaranty Company (NGC) and similar.
- Certificate numbers that don't match the coin, grade or date shown online.
- Too-good key dates: counterfeits and altered dates and mint marks are common.
Common fakes: coins →Sourced screening tips.
Free lookups
PCGS CoinFacts ↗Coin details, mintages and photos by date.PCGS certificate verification ↗Check a PCGS holder's certificate number.NGC price guide ↗Retail price guide for United States and world coins.NGC certificate lookup ↗Check an NGC holder's certificate number.NGC Coin Explorer ↗Specs, mintages and varieties.Certified Acceptance Corporation (CAC) ↗Sticker and grading verification.Heritage Auctions coins ↗Past auction results (free account may be needed).eBay sold listings ↗Search completed sales, not asking prices.
These guides are general information, not appraisals. Links go to independent sites we don't control and aren't affiliated with.
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