But what are examples of such stamps? How do you know when a stamp is a true condition rarity? How can you judge what constitutes exceptional quality for a particular issue? The answer is acquiring all the background knowledge that you can about the issue in question.
The examples I am going to use in this post relate to Canadian stamps, but the principles are the same for any country and you should read it with that in mind if you collect a country other than Canada.
Now for the examples. Consider these four stamps from New Brunswick that I am currently selling: