Katalognumre på frimærker: AFA, Michel, Scott og Stanley Gibbons

What is a stamp catalogue number?

It's the ID that identifies one specific stamp issue, including its design, denomination, perforation, watermark and printing. Dealers, auctions and collectors use it so everyone knows exactly which stamp is being discussed.

“US 2¢ Washington” describes dozens of different stamps worth anything from cents to hundreds of dollars. “Scott 499” describes exactly one. That precision is the whole point, and it's why listings that quote a catalogue number are easier to trust than ones that don't.

Which stamp catalogue should I use?

Use the one used where you buy and sell: Scott in the United States, Stanley Gibbons in Britain and the Commonwealth, Michel in Germany and much of Europe, and Yvert in France.

The catalogues also differ in how they split varieties and how they price. A stamp listed once in Scott may have three numbers in a specialized catalogue.

What do letter prefixes in Scott numbers mean?

They mark categories outside ordinary postage. C is airmail, B is semi-postal, J is postage due, O is official, R is revenue and RW is the federal duck stamps.

Suffix letters matter too. A lowercase letter usually marks a variety, so Scott C3a is the Inverted Jenny rather than the normal C3.

What does catalogue value actually mean?

It's a reference retail price for that stamp in a stated grade, not the price you'll be paid. Common stamps usually sell well below catalogue, and exceptional copies can sell above it.

Catalogues also apply a minimum value to the cheapest stamps, which reflects a dealer's handling cost rather than what a single stamp fetches. Two catalogues can quote different values for the same stamp, because they price different grades and different markets. See what are my stamps worth?

How do I find the catalogue number for my stamp?

Identify the country, year and denomination first, then narrow by perforation, watermark and printing method, and match that against the catalogue's listing for the issue.

1. Work out the country from the inscription or design.
2. Read the denomination and currency.
3. Estimate the year from the design, portrait or printed date.
4. Check perforation gauge and watermark if the catalogue splits the issue.
5. Match the listing, then note the number with your inventory record.

How to identify stamps covers each of those steps, and how to organize a stamp collection explains where to record the number.

How do catalogue numbers help when buying and selling?

They remove ambiguity. A number tells a buyer exactly which stamp, printing and variety is on offer, which makes listings searchable, offers comparable and disputes rare.

• Selling: a listing with a catalogue number and a condition grade attracts serious buyers. One that says “old rare stamp” attracts nobody who knows the market.
• Buying: you can compare like with like across dealers and auctions, and check recent sold prices for that exact number.
• Want lists: dealers work from numbers, so a list of numbers gets you the right stamps by post.
• Insurance and estates: an inventory of numbers and grades is far easier to value than a description of album pages.

Include the catalogue name as well as the number, because the same stamp has different numbers in Scott, SG and Michel. “SG 429” and “Scott 499” are not interchangeable, and quoting only a bare number invites confusion. See how to sell stamps.