While it is difficult to direct someone trying identify a mark on porcelain without seeing the actual piece in question, an expert would advise that the “N” mark most often associated with Italian porcelain items is that of Capodimonte. The signature known as the “crown and Neapolitan N” mark, originally referring to wares made by the Royal Factory in Naples, Italy, in the 1700s, was repeated in several different iterations over the years and copied by other companies as well.
Examine the at the mark on your piece of porcelain, using a magnifying glass or jeweller's loupe if needed.
See if the mark has a crown over an "N." If so, your piece could be Capodimonte.
Look at the subtleties of the way the “N” is formed, and the way the crown is shaped. Click on the link to Antiques in the Resources section. If you have the exact mark shown there, your Capodimonte piece was made between 1771 and 1834. If the mark is not an exact match to that example, continue to Step 4.
See if the mark on your piece has a straighter “N” and a more stylised crown, compare your mark to those shown on Onlinecollectibles.com listed in the Resources section. There were several other marks similar to the oldest Capodimonte mark used during other periods, and you will find dating information (as well as other Capodimonte marks) there.
Keep in mind that the original producer of this type of porcelain was not actually named Capodimonte, so the word Capodimonte refers to a style as well as the name used by antiques dealers and collectors use to describe pieces marked with the crown and Neapolitan N mark.