Collectors apply different values to old stamps, depending on several factors. The worth of an old stamp is partially determined by demand. Another source of value is in how many of the old stamps were in circulation. For instance, one rare and valuable stamp is the one cent U.S. commemorative postage stamp from 1898 depicting the "Marquette on the Mississippi" with a total of 70,993,400 in circulation.

Demand

Demand is how much a collector is willing to pay to purchase a particular old stamp. If an older stamp is more common, a collector will not pay as much money for it. If it turns out to be rare, the stamps will be worth more money.

Considerations

Stamps stay healthiest---and retain their optimum value---when stored in a cool, dry place. Humidity or moisture can devastate an old stamp's value. A well-cared for collection must be kept in an upright album without any added pressure---force on an album can cause stamps to stick to pages.

Identification

Detailed appraisals demand extensive examination of each individual item. Old stamp appraisals can be expensive. Some firms charge a flat hourly or daily fee, plus travel expenses if required. Working with a fixed fee ensures a collector that the dealer will perform a certain amount of expert research.

Cataloging

Stamp catalogs in local libraries act as an easily accessible expert resource for collectors. A stamp's value can be found through investigative research.

Research Methods

A website like Find Your Stamp's Value can also help you investigate your stamp's worth. To determine the stamp's denomination, inscription, water mark and printing method, a website database supplies a detailed historical database of stamp colors, depictions, inscriptions and more.

Expert Insight

Experienced collectors and catalog users automatically assume their stamp is rare and then exhaustively search the catalog to find the more common variety. This can minimize a collector's excitement but increase his research credibility.

Source:

Find Your Stamp's Value- How it works

American Philately Society - estate services

1847 USA - stamp values research page

Resource:

American Philatelic Society

Find Your Stamp's Value - how to search online database

1847 USA- Commemorative stamps reference page