Print colour should be fresh, not faded.- There should be no marks or scratches.
- The gum should have a smooth colour.
- There should be no tone spots _ marks of a brown, rusty appearance _ on either side of the stamp.
- Hinge remnants, where the stamp has torn away rather than letting go of the stamp, should be clear and clean and not thick and dirty.
- The perforation teeth surrounding the stamp should look nice, not be too short or torn.
- For cancelled stamps, the same guidelines should be used but note the postmark. The stamp should have a clear cancellation mark but not too heavy, as that could affect its price.
- In other words, the price of a stamp in good condition can be higher than the catalogue or even market price.
Source: View original article