Now that you know how to grade the condition of your stamps, you may feel ready to either purchase or sell some stamps. However, if you are dealing in Mint stamps, there is another factor you need to understand in order to determine the proper value—the never hinged surcharge (NH%). This is a percentage to be added to the regular price (the value of a mint previously hinged stamp); this will give you the final value of a stamp that has never been hinged. For Canadian stamps, the never hinged surcharge value of each stamp is established and printed in the Unitrade Specialized Catalogue of Canadian Stamps and represented by the NH% symbol.