1. The printing color is fresh, not faded.
2. No mark or scratch on the stamp/sheet.
3. The gum on the back of the stamp/sheet has smooth color.
4. No rust or tone spot on both side of the stamp/sheet.
5. For hinge remnant stamp, should select clear and clean hinge and
avoid thick and dirty hinge.
6. Perforation teeth that surround each stamp should be nice, not be
short or torn.