Valuation
How Stanley Gibbons Catalogue Value Works
The Stanley Gibbons (SG) catalogue is the standard reference for British and Commonwealth stamps. It gives every stamp a unique SG number and a guide price for a fine example bought from a dealer, with separate figures for mint and used. The prices are a guide for identifying and comparing stamps, not the amount a stamp will sell for, and very common stamps are listed at a minimum catalogue price that does not reflect their modest real value.
At a glance
What the Stanley Gibbons catalogue is
Stanley Gibbons is the long-established standard catalogue for the stamps of Great Britain and the Commonwealth, and the reference that collectors and dealers share. When someone quotes an "SG number" or a catalogue value for a British stamp, this is almost always what they mean.
It is published in several different titles, from simple checklists to detailed specialist volumes, so that collectors can choose the depth they need.
How SG numbers work
Every stamp has its own SG number, which is the standard way to identify it precisely. For Great Britain, the numbers run broadly in order of issue, beginning with SG 1, the Penny Black.
Varieties, such as different shades, perforations, watermarks or errors, are shown with suffix letters, for example a number followed by "a" or "b", or are given numbers of their own. One thing to watch is that different Stanley Gibbons catalogues can give the same stamp different numbers, especially the specialised volumes, which break detailed varieties out separately. It is always worth noting which catalogue a number comes from.
How SG prices are set
The prices in the catalogue reflect a stamp in fine condition, bought from a dealer at retail. Two figures are usually shown, one for mint and one for used, and for older issues the mint figure may distinguish unmounted mint from mounted mint.
These are guide prices, revised in each new edition rather than tracking the market day to day. Condition then moves the real figure up or down: a faulty or poorly centred stamp is worth less than the catalogue price, while a superb example can be worth more.
What a catalogue entry contains
- SG number
- A unique reference that identifies the stamp exactly.
- Description
- The issue, denomination, colour and any key detail.
- Mint price
- A guide price for a fine unused example, bought from a dealer.
- Used price
- A guide price for a fine postally used example.
The minimum catalogue price
The part that most often misleads
A large catalogue total can mean very little
Stanley Gibbons sets a minimum price, below which very common stamps are not individually valued. A great many stamps are catalogued at this floor figure, simply because they are common and inexpensive. A stamp listed at the minimum is not worth that as a selling price; the figure only marks it as common.
The effect is striking on a whole collection. A thick album full of minimum-priced stamps can add up to a large catalogue total while being worth very little in reality. It is one of the main reasons a collection is so often worth far less than its catalogue figure suggests, as our guide to catalogue value versus market value explains.
Which Stanley Gibbons catalogue to use
- For general Great Britain collecting, a checklist-style or concise catalogue gives the numbers and guide prices most people need.
- For detailed study of varieties, shades, plates and printings, the specialised Great Britain volumes go much further, down to individual plate numbers.
- For the wider world, the simplified worldwide catalogue and the country and Commonwealth volumes cover stamps beyond Britain.
How to read SG values sensibly
Used well, the catalogue is invaluable. Use the SG number to identify a stamp exactly, and the catalogue value as a guide and a way to compare one stamp with another.
Just do not read the figure as a selling price. The amount a stamp actually realises is usually well below catalogue, it assumes fine condition, and for common stamps the minimum price tells you almost nothing about real worth. For a realistic figure, look at what comparable stamps have actually sold for, or ask for a valuation.
Frequently asked questions
A unique reference number that identifies a particular stamp. For Great Britain the numbers run broadly in order of issue, starting with SG 1, the Penny Black.
It is a guide price for a fine example bought from a dealer, not a selling price. What a stamp actually sells for is usually well below catalogue.
Because many common stamps are listed at the minimum catalogue price. A large catalogue total made up of minimum-priced stamps reflects quantity, not value.
A concise or checklist catalogue covers general collecting, while the specialised volumes break out detailed varieties, shades and plates for in-depth study.
Yes. The catalogue usually gives separate mint and used figures, and for older issues the mint figure may distinguish unmounted from mounted mint.
Looking to buy?
Browse our Great Britain stamps, each listed with its SG number, or explore the full shop.
Founder and stamp dealerLast updated June 2026