Here’s a list, accompanied by images, of coin grading company slabs you should avoid at all costs. If you don’t know much about grading coins (most of us don’t, even if we think we do) or can’t see a clear image, with which to grade the coin, then do yourself a favor and move on to better auctions.
I have read too many regret stories from collectors who didn’t know they were buying an over-graded coin. All of them thought that if it was in a professional looking holder then it must be graded properly. A few thought they were grabbing a bargain.
Note: Some of these holders might appear with a different design or label color, and might be sold by multiple ebay sellers. However, most are sold by a single ebay seller in large quantities.
NNC National Numismatic Certification
SGS Star Grading Service
ANGS American Numismatic Grading Service
NAC Numismatic Authentication Company
NCC Numismatic Collectors Company
NES Numismatic Evaluation Service
NPG Numismatic Professional Grading
CSI Certified Silver Investments
USGS US Coin Grading
You should avoid most no-name holders since they’re just coins graded by the person selling the coins, as are most over-grading coin companies and services. If you can’t see a clear and detailed image, without glare or “masking” angles and lighting then don’t bid on the coin, no matter what the holder label claims.