Most Valuable US Stamps: Record Prices and Why

The most valuable American stamp is the 1868 one-cent Benjamin Franklin Z grill, Scott 85A, which sold for US$4,366,000 at Robert A. Siegel Auction Galleries in June 2024 as part of the William H. Gross collection. That session was described by the auctioneer as the highest-grossing single session in philatelic history, and the collection made about US$19.2 million in all.

The rest of the American top tier:

• 1867 15-cent Lincoln Z grill (Scott 85F) — US$2,773,000, Siegel, June 2024
• 1918 24-cent Inverted Jenny, position 49, graded 95 and never hinged — US$2,006,000, Siegel, 11 November 2023; the same stamp had made US$1,593,000 at Siegel in November 2018
• Inverted Jenny plate block of four — US$2,970,000 at Siegel in October 2005, then traded to Bill Gross for the Z grill
• 1847 Alexandria "Blue Boy" cover — US$1,180,000, H.R. Harmer New York, 22 June 2019

Every price above includes the 18 per cent buyer's premium the house adds to the hammer price.

In 1867 the Post Office Department had a problem: people were washing cancellation ink off used stamps and posting them again. The fix was a grill — a roller that pressed a pattern of tiny pyramids into the paper so the ink soaked into broken fibres and could not be washed out.

Several grill patterns were tried in quick succession and each got a letter. The Z grill is identified by ridges running horizontally across the impression, where every other grill has vertical ridges; the grilled area measures roughly 11 by 14 millimetres. Z grills were used for only a few weeks — the earliest known postmarks on them date from January 1868 — before the pattern was changed again.

That short window is the whole story. On the 1-cent Franklin and the 15-cent Lincoln, only two examples of each are known to have survived. One of the two 1-cent Z grills sits in the Benjamin Miller collection at the New York Public Library and will never come to market, so a collector who wants one is competing for a single stamp.

Grills are checked by looking at the back of the stamp in raking light, and they are routinely faked. Any stamp thought to carry a scarce grill needs a certificate from an expertising committee before anyone should pay for it.

The 1869 Pictorial Issue was the first US series printed in two colours, on the 15-cent, 24-cent, 30-cent and 90-cent values. Two-colour printing means two passes through the press, and a sheet fed in the wrong way round on the second pass produces an inverted centre. The 15-cent, 24-cent and 30-cent inverts of 1869 are America's first invert errors.

The same mechanism produced the Inverted Jenny half a century later. The 24-cent airmail stamp of 10 May 1918 carried a Curtiss JN-4 biplane in a carmine frame; on one sheet of 100 the plane came out upside down. William T. Robey bought that sheet at a Washington post office on 14 May 1918, sold it to the dealer Eugene Klein for $15,000, and Klein resold it to Colonel Edward Green for $20,000. Of the 100 stamps, about 93 are accounted for; the rest are lost or destroyed.

Modern reprints and souvenir sheets of the Inverted Jenny exist and are worth a few dollars. The Inverted Jenny page explains how to tell a 1918 original from them.

Most of what turns up in an American shoebox is common. The Liberty, Prominent Americans and Great Americans definitive series were printed in the billions and used examples are worth cents, not dollars. Elvis commemoratives from 1993, Bugs Bunny from 1997 and holiday Forever stamps were bought and saved in huge numbers precisely because people expected them to appreciate, which is why they did not.

Unused modern stamps still have their postage value, which is their real floor: a mint Forever stamp is worth the current first-class rate regardless of what year it was issued.

The place to check ordinary US definitives is our US definitive stamp identifier, which lists the series, years and design details so you can match a stamp to a catalogue number before looking up a value.

The expensive American stamps are defined by features you cannot see from across a room: a grill pattern on the back, a perforation gauge, a watermark, a plate variety, the centring of the design inside the margins. A stamp that matches the picture in a catalogue is not the same as a stamp that matches the listing.

A sensible order of work is to identify the issue, then measure the perforations and check for a watermark, then compare condition honestly, and only then look at price. Our guide to perforations and watermarks covers the two measurements that separate most look-alikes.

Photograph the stamp and the app identifies it, which gives you a starting catalogue number to check the rest against.