As with coins and baseball cards, in recent years some stamp collectors have started submitting their stamps to grading agencies for "expertising". Some of the well-known organizations which issue certs for stamps include PSE, Weiss, PF and APS.
Some stamps will be sold with an existing cert, and other sellers will offer the buyer the opportunity to have a stamp graded and examined by a third party before completing the transaction. As with any collecting purchase, cert or not, caveat emptor!
Best of the Web (“Hall of Fame”)
The Stamp Collecting Round-up
Don Schilling's long-running, in-depth blog on stamp collecting and postal operations. Schilling stays up on all th… [read review or visit site]
National Postal Museum
If you're into postal history or collectibles, check out the Smithsonian's National Postal Museum. This extensive s… [read review or visit site]
Post Office in Paradise
Post Office in Paradise showcases Hawaiian postal history from the years before Hawaii became a part of the United … [read review or visit site]
Private Die Proprietary Stamps
Bob Hohertz's impressive database of U.S. Private Die Proprietary stamps from the Civil War and Spanish American Wa… [read review or visit site]
First shown in 2008 to celebrate the Smithsonian National Postal Museum's 15th anniversary, Alphabetilately is esse… [read review or visit site]
Clubs & Associations
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