Non-denominated (First-Class Forever) Liberty Bell Stamp (2007): How to Identify It

• Design subject: the Liberty Bell, rung in 1776 to announce the reading of the Declaration of Independence, a national symbol of freedom.
• Issue location: the Postal Service's first Forever stamp, featuring the Liberty Bell, was issued April 12, 2007, at Philadelphia's Independence Hall.

The same design was issued in more than one form. Which one you have changes the catalog listing:

• Booklet of 20 self-adhesive (Scott 4125a and related): Sold as a self-adhesive booklet rather than a traditional gummed sheet stamp; no perforations are visible on booklet-die-cut edges the way they are on classic sheet stamps.
• ATM booklet pane (Scott 4128/4128a): A smaller pane sold through automated postal machines rather than post-office retail counters.
• 2010 reprint (Scott 4437): The same Liberty Bell Forever design was reprinted in 2010 with a new Scott catalog number; compare printing-year references on dealer listings rather than the design itself to date a specific example.

Forever stamps are non-denominated postage stamps that retain their mailing value regardless of subsequent postal rate increases -- buyers pay the current first-class rate but can use them indefinitely, so people hold onto and keep buying them for years, and the 2007 Liberty Bell printing alone sold about 1.2 billion copies by that July.

• Measure the perforations with a gauge; the same design often exists in two or three gauges, and that is usually what separates the common one from the scarce one.
• Sheet, coil or booklet: coils have two straight edges on opposite sides; booklet panes have one or two straight edges from the pane edge.
• Tagging: hold it under a longwave UV lamp; tagged and untagged printings of the same design are listed separately.
• Condition (centering, gum, cancel) is a separate question from identification.

Lay the stamp flat on a dark background in daylight, fill the frame, and keep the phone parallel so the perforations are not distorted. Photograph the back too if there is a watermark or gum question. The app reads the design and denomination; the perforation and tagging checks above settle which listing it is.